Added readme

README.md

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+# Brigadier
+Brigadier is a command parser & dispatcher, designed and developed for Minecraft: Java Edition and now freely available for use elsewhere under the MIT license.
+
+# Installation
+Brigadier is available to Maven & Gradle via `libraries.minecraft.net`. Its group is `com.mojang`, and artifact name is `brigadier`.
+
+## Gradle
+First include our repository:
+```groovy
+maven {
+    url "https://libraries.minecraft.net"
+}
+```
+
+And then use this library (change `(the latest version)` to the latest version!):
+```groovy
+compile 'com.mojang:brigadier:(the latest version)'
+```
+
+## Maven
+First include our repository:
+```xml
+<repository>
+  <id>minecraft-libraries</id>
+  <name>Minecraft Libraries</name>
+  <url>https://libraries.minecraft.net</url>
+</repository>
+```
+
+And then use this library (change `(the latest version)` to the latest version!):
+```xml
+<dependency>
+    <groupId>com.mojang</groupId>
+    <artifactId>brigadier</artifactId>
+    <version>(the latest version)</version>
+</dependency>
+```
+
+# Contributing
+Contributions are suspended until we have a process in place to handle them.
+
+Most contributions will require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to,
+and actually do, grant us the rights to use your contribution. For details, visit https://cla.microsoft.com.
+
+This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/).
+For more information see the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or
+contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with any additional questions or comments.
+
+# Usage
+At the heart of Brigadier, you need a `CommandDispatcher<S>`, where `<S>` is any custom object you choose to identify a "command source".
+
+A command dispatcher holds a "command tree", which are a series of `CommandNode` which represent the various possible syntax that form a valid command.
+
+## Registering a new command
+Before we can start parsing and dispatching commands, we need to build up our command tree. Every registration is an append operation,
+so you can freely extend existing commands in a project without needing access to the source code that created them.
+
+Command registration also encourages use of a builder pattern to keep code cruft to a minimum.
+
+A "command" is a fairly loose term, but typically it means an exit point of the command tree.
+Every node can have an `executes` function attached to it, which signifies that if the input stops here then this function will be called with the context so far.
+
+Consider the following example:
+```java
+CommandDispatcher<CommandSourceStack> dispatcher = new CommandDispatcher();
+
+dispatcher.register(
+    literal("foo")
+        .then(
+            argument("bar", integer())
+                .executes(c -> {
+                    System.out.println("Bar is " + getInteger(c, "bar"));
+                    return 1;
+                })
+        )
+        .executes(c -> {
+            System.out.println("Called foo with no arguments");
+            return 1;
+        })
+);
+``` 
+
+This snippet registers two "commands": `foo` and `foo <bar>`. It is also common to refer to the `<bar>` as a "subcommand" of `foo`, as it's a child node.
+
+At the start of the tree is a "root node", and it **must** have `LiteralCommandNode`s as children. Here, we register one command under the root: `literal("foo")`, which means "the user must type the literal string 'foo'".
+
+Under that is two extra definitions: a child node for possible further evaluation, or an `executes` block if the user input stops here.
+
+The child node works exactly the same way, but is no longer limited to literals. The other type of node that is now allowed is an `ArgumentCommandNode`, which takes in a name and an argument type.
+
+Arguments can be anything, and you are encouraged to build your own for seamless integration into your own product. There are some standard arguments included in brigadier, such as `IntegerArgumentType`.
+
+Argument types will be asked to parse input as much as they can, and then store the "result" of that argument however they see fit or throw a relevant error if they can't parse.
+
+For example, an integer argument would parse "123" and store it as `123` (`int`), but throw an error if the input were `onetwothree`.
+
+When a command is actually ran, it can access these arguments in the context provided to the registered function.
+
+## Parsing user input
+So, we've registered some commands and now we're ready to take in user input. If you're in a rush, you can just call `dispatcher.execute("foo 123", source)` and call it a day.
+
+The result of `execute` is an integer returned by the command it evaluated. Its meaning varies depending on command, and typically will not be useful to programmers.
+
+The `source` is an object of `<S>`, your own custom class to track users/players/etc. It will be provided to the command so that it has some context on what's happening.
+
+If the command failed or could not parse, some form of `CommandSyntaxException` will be thrown. It is also possible for a `RuntimeException` to be bubbled up, if not properly handled in a command.
+
+If you wish to have more control over the parsing & executing of commands, or wish to cache the parse results so you can execute it multiple times, you can split it up into two steps:
+
+```java
+final ParseResults<S> parse = dispatcher.parse("foo 123", source);
+final int result = execute(parse);
+``` 
+
+This is highly recommended as the parse step is the most expensive, and may be easily cached depending on your application.
+
+You can also use this to do further introspection on a command, before (or without) actually running it.
+
+## Inspecting a command
+If you `parse` some input, you can find out what it will perform (if anything) and provide hints to the user safely and immediately.
+
+The parse will never fail, and the `ParseResults<S>` it returns will contain a *possible* context that a command may be called with
+(and from that, you can inspect which nodes the user entered, complete with start/end positions in the input string).
+It also contains a map of parse exceptions for each command node it encountered. If it couldn't build a valid context, then
+the reason why is inside this exception map.
+
+## Displaying usage info
+There's two forms of "usage strings" provided by this library, both require a target node.
+
+`getAllUsage(node, source, restricted)`  will return a list of all possible commands (executable end-points) under the target node and their human readable path. If `restricted`, it will ignore commands that `source` does not have access to. This will look like [`foo`, `foo <bar>`]
+
+`getSmartUsage(node, source)` will return a map of the child nodes to their "smart usage" human readable path. This tries to squash future-nodes together and show optional & typed information, and can look like `foo (<bar>)`
+