Add migration docs

docs/migrating-from-beta.md

@@ -0,0 +1,18 @@
+# Migrating from RAPIDS beta
+
+If you were relying on the [old docs](https://rapidspitt.readthedocs.io/en/latest/) and the most recent version of RAPIDS you downloaded is from or before [Oct 13, 2020](https://github.com/carissalow/rapids/commit/640890c7b49492d150accff5c87b1eb25bd97a49) you are using the beta version of RAPIDS.
+
+You can start using the new RAPIDS (we are starting with `v0.1.0`) right away, just take into account the following:
+
+1. [Install](setup/installation.md) a new copy of RAPIDS (the R and Python virtual environments didn't change so the cached versions will be reused)
+      1. Make sure you don't skip a new Installation step to give execution permissions to the RAPIDS script: `chmod +x rapids`
+2. Follow the new [Configuration](setup/configuration.md) guide.
+      1. You can copy and paste your old `.env` file
+      2. You can migrate your old participant files: 
+      ```
+      python tools/update_format_participant_files.py
+      ```
+3. You can proceed to reconfigure your `config.yaml`, its structure is more consistent and should be familiar to you.
+
+!!! info
+    If you have any questions reach out to us on [Slack](http://awareframework.com:3000/).

mkdocs.yml

@@ -108,6 +108,7 @@ nav:
     - Testing: developers/testing.md
     - Test cases: developers/test-cases.md
   - Others:
+    - Migrating from RAPIDS beta: migrating-from-beta.md
     - Code of Conduct: code_of_conduct.md
     - Frequently Asked Questions: faq.md
     - Team: team.md