Add a README

Author: kddnewton

README.md

@@ -0,0 +1,82 @@
+# SyntaxTree::XML
+
+[![Build Status](https://github.com/ruby-syntax-tree/syntax_tree-xml/actions/workflows/main.yml/badge.svg)](https://github.com/ruby-syntax-tree/syntax_tree-xml/actions/workflows/main.yml)
+[![Gem Version](https://img.shields.io/gem/v/syntax_tree-xml.svg)](https://rubygems.org/gems/syntax_tree-xml)
+
+[Syntax Tree](https://github.com/ruby-syntax-tree/syntax_tree) support for XML.
+
+## Installation
+
+Add this line to your application's Gemfile:
+
+```ruby
+gem "syntax_tree-xml"
+```
+
+And then execute:
+
+    $ bundle install
+
+Or install it yourself as:
+
+    $ gem install syntax_tree-xml
+
+## Usage
+
+From code:
+
+```ruby
+require "syntax_tree/xml"
+
+pp SyntaxTree::XML.parse(source) # print out the AST
+puts SyntaxTree::XML.format(source) # format the AST
+```
+
+From the CLI:
+
+```sh
+$ stree ast --plugins=xml file.xml
+(document
+  (misc "\n"),
+  (element
+    (opening_tag "<", "message", ">"),
+    (char_data "\n" + "  "),
+    (element (opening_tag "<", "hello", ">"), (char_data "Hello"), (closing_tag "</", "hello", ">")),
+    (char_data "\n" + "  "),
+    (element (opening_tag "<", "world", ">"), (char_data "World"), (closing_tag "</", "world", ">")),
+    (char_data "\n"),
+    (closing_tag "</", "message", ">")
+  )
+)
+```
+
+or
+
+```sh
+$ stree format --plugins=xml file.xml
+<message>
+  <hello>Hello</hello>
+  <world>World</world>
+</message>
+```
+
+or
+
+```sh
+$ stree write --plugins=xml file.xml
+file.xml 1ms
+```
+
+## Development
+
+After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake test` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
+
+To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
+
+## Contributing
+
+Bug reports and pull requests are welcome on GitHub at https://github.com/ruby-syntax-tree/syntax_tree-xml.
+
+## License
+
+The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).