[DOC] Add contributing guide to readme and check if tests pass to PR …

…template (#987)

## Description of changes

*Summarize the changes made by this PR.*
 - Improvements & Bug fixes
- Add contributing guide to readme and a check if tests pass to PR
template
 - New functionality
	 - None
	 

Addresses #968

## Test plan
These are documentation changes. No tests required.

## Documentation Changes
These are documentation changes.

README.md

@@ -96,6 +96,7 @@ Chroma is a rapidly developing project. We welcome PR contributors and ideas for
 - [Join the conversation on Discord](https://discord.gg/MMeYNTmh3x) - `#contributing` channel
 - [Review the 🛣️ Roadmap and contribute your ideas](https://docs.trychroma.com/roadmap)
 - [Grab an issue and open a PR](https://github.com/chroma-core/chroma/issues) - [`Good first issue tag`](https://github.com/chroma-core/chroma/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22)
+- [Read our contributing guide](https://docs.trychroma.com/contributing)
 
 **Release Cadence**
 We currently release new tagged versions of the `pypi` and `npm` packages on Mondays. Hotfixes go out at any time during the week.

pull_request_template.md

@@ -9,5 +9,7 @@
 ## Test plan
 *How are these changes tested?*
 
+- [ ] Tests pass locally with `pytest` for python, `yarn test` for js
+
 ## Documentation Changes
 *Are all docstrings for user-facing APIs updated if required? Do we need to make documentation changes in the [docs repository](https://github.com/chroma-core/docs)?*