Add README.md with Install & Building Instructions

[rhass]

It would be nice if there was a README.md in the repo indicating how to build and install this plugin. I tried building it via CLI and IntelliJ (2017.2.2) but encountered different issues for each approach.

[s5bug]

See #1 for a temporary plugin build.

Building with IntelliJ does not work at the moment, you have to run the build in the Gradle plugin at the moment. This will drop a zip file in target which you can add as a plugin.

[bararchy]

I would also love some examples in the front (README) :)

[exts]

@TsundereBug you should add this as an official plugin so we can just install via plugin manager. https://plugins.jetbrains.com

[faustinoaq]

Hi, a intellij-crystal plugin is already published here: http://plugins.jetbrains.com/plugin/10213-crystal-language-plugin

Also I forked that repo here: https://github.com/crystal-lang-tools/intellij-crystal-lang

[faustinoaq]

I guess https://plugins.jetbrains.com/plugin/10213-crystal-language-plugin is a better option now, I gonna publish a new version soon

@TsundereBug Thank you for you work here, was very appreciated! ❤️ 👍