Add more docs for contributing (#9)

* Make the pre-commit hook use the stylua binary installed on the system
* Add docs for contributing

.pre-commit-config.yaml

@@ -2,4 +2,4 @@ repos:
 - repo: https://github.com/JohnnyMorganz/StyLua
   rev: v0.17.1
   hooks:
-    - id: stylua-github
+    - id: stylua-system

README.md

@@ -164,6 +164,27 @@ A customizable Neovim plugin to run code inside the editor
 
 ## Contribution
 
-  If you find that some handlers for a specific language are missing, feel free to open a pull request by adding them in the [lua/runner/handlers/init.lua](lua/runner/handlers/init.lua) file.
+  This project uses [StyLua](https://github.com/JohnnyMorganz/StyLua) for enforcing code style, and has a [pre-commit](https://pre-commit.com/) hook setup for running it automatically. `runner.nvim` also has a Github Action that runs the linter on every Pull request. If a check doesn't pass on a specific Pull request, please lint the code and commit it again.
+
+  For running them locally, you have to have them installed on your system:
+  - [StyLua Installation](https://github.com/JohnnyMorganz/StyLua#installation)
+  - [pre-commit Installation](https://pre-commit.com/#install) 
+
+  #### Some useful commands:
+
+  - Install the pre-commit hook
+    ```bash
+    pre-commit install
+    ```
+
+  - Check for StyLua errors
+    ```bash
+    stylua --check lua/
+    ```
+    
+  - Fix StyLua errors
+    ```bash
+    stylua lua/
+    ```
   
   Licensed under the [MIT license](./LICENSE).