Update contributing guide with a getting started section

Author: isc-dchui

CONTRIBUTING.md

@@ -1,7 +1,17 @@
-# How to contribute
+# How to Contribute
 
 Thank you for your interest in contributing! While this project originated at InterSystems, it is our hope that the community will continue to extend and enhance it.
 
+## Getting Started
+
+We recommend setting up a local development instance by following these steps:
+1. Install an instance of IRIS (go to https://evaluation.intersystems.com/ for an evaluation kit).
+2. Install IPM (InterSystems Package Manager) (https://github.com/intersystems/ipm).
+3. Clone a copy of the Embedded Git repository to disk using `git clone`.
+4. Install Embedded Git using IPM by running this terminal command (`zpm "load <path_to_embedded_git_repo_directory> -dev"`).
+5. Configure your Embedded Git instance to point at a Git repository that IS NOT Embedded Git (it can get very messy very quickly).
+6. Modify the code locally! Note that any changes to CSP pages will require loading the module again with IPM to propagate the changes to your local instance.
+
 ## Submitting changes
 
 If you have made a change that you would like to contribute back to the community, please send a [GitHub Pull Request](/pull/new/main) explaining it. If your change fixes an issue that you or another user reported, please mention it in the pull request. You can find out more about pull requests [here](http://help.github.com/pull-requests/).
@@ -10,17 +20,16 @@ Every pull request should include at least one entry in CHANGELOG.md - see [keep
 
 We encourage use of [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/).
 
-## Coding conventions
+## Coding Conventions
 
 Generally speaking, just try to match the conventions you see in the code you are reading. For this project, these include:
 
-* Do not use shortened command and function names. For example, use `set` instead of `s` and `$piece` instead of `$p`
+* Use the full command and function names. For example, use `set` instead of `s` and `$piece` instead of `$p`
 * One command per line
-* Do not use dot syntax
 * Indentation with tabs
 * [Pascal case](https://en.wikipedia.org/wiki/Camel_case) class and method names
-* Avoid using postconditionals
-* Local variables start with `t`; formal parameter names start with `p`
+* Avoid dot syntax
+* Avoid postconditionals
 * Always check %Status return values
 
 When making changes that involve JavaScript, ensure that your changes still work from Studio (which uses an old version of IE under the hood and therefore doesn't support various things you might take for granted).