Add CONTRIBUTING.md (#725)

* * Add contributing
* Update run platform script user guide in README
* Update encryption key backup reminder in README

* Fix contributing md doc link in readme

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Ritwik G <100672805+ritwik-g@users.noreply.github.com>

Author: 3 people

CONTRIBUTE.md

@@ -0,0 +1,3 @@
+# Contributing
+
+See [docs.unstract.com](https://docs.unstract.com/contributing/unstract).

CONTRIBUTING.md

@@ -58,6 +58,7 @@ Next, either download a release or clone this repo and do the following:
 
 That's all there is to it!
 
+See [user guide](https://docs.unstract.com/unstract_platform/user_guides/run_platform) for more details on managing the platform.  
 Another really quick way to experience Unstract is by signing up for our [hosted version](https://us-central.unstract.com/).
 
 ## ⏩ Quick Start Guide
@@ -137,14 +138,20 @@ Unstract comes well documented. You can get introduced to the [basics of Unstrac
 
 ## 🙌 Contributing
 
-Contributions are welcome! Please read [CONTRIBUTE.md](CONTRIBUTE.md) for further details on setting up the development environment, etc. It also points you to other detailed documents as needed.
+Contributions are welcome! Please read [CONTRIBUTING.md](CONTRIBUTING.md) for further details on setting up the development environment, etc. It also points you to other detailed documents as needed.
 
 ## 👋 Join the LLM-powered automation community
 
 - On Slack, [join great conversations](https://join-slack.unstract.com) around LLMs, their ecosystem and leveraging them to automate the previously unautomatable!
 - [Follow us on X/Twitter](https://twitter.com/GetUnstract)
 - [Follow us on LinkedIn](https://www.linkedin.com/showcase/unstract/)
 
+## 🚨 Backup encryption key
+
+Do copy the value of `ENCRYPTION_KEY` config in either `backend/.env` or `platform-service/.env` file to a secure location.  
+
+Adapter credentials are encrypted by the platform using this key. Its loss or change will make all existing adapters inaccessible!  
+
 ## 📊 A note on analytics
 
 In full disclosure, Unstract integrates Posthog to track usage analytics. As you can inspect the relevant code here, we collect the minimum possible metrics. Posthog can be disabled if desired by setting `REACT_APP_ENABLE_POSTHOG` to `false` in the frontend's .env file.