Add missing mention of Safe Mode; add more notes for upgrading

Author: jcsalterego

README.md

@@ -39,6 +39,8 @@ The longer (and incomplete) instructions can be found in [INSTALL.md](INSTALL.md
 
 ## Upgrading
 
+The first step before any major upgrade is to make a copy of your markdown config file. Your best bet is to save it in a separate directory such as `backup_configs/`, or you will have to remember to set `isEnabled` to false so it doesn't get picked up as a live config!
+
 In the event you'd like to pull in the latest changes into a fork of Contrails, GitHub has great documentation here:
 [GitHub Docs: Syncing a fork](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork)
 
@@ -47,6 +49,7 @@ In the event you'd like to pull in the latest changes into a fork of Contrails,
 ### 0.2.0
 
 * Pagination
+* Safe Mode
 
 ### 0.1.0