Add admin panel feature info to readme and heroku

HEROKU.md

@@ -21,6 +21,7 @@ After clicking the Heroku button above:
 6. (optional) Copy and paste your Google/YouTube API key into the `GOOGLE_API_KEY` field.
 7. (optional) Copy and paste your Vimeo API key into the `VIMEO_API_KEY` field.
 8. (optional) If you have a Google Analytics account, you can paste your site tracking code into the `GA_TRACKING_CODE` field.
+9. (optional) If you would like to enable the Admin Panel, change the `ADMIN_PANEL_ENABLED` field to `true`.
 8. Click the Deploy button and wait for the process to complete.
 
 ### Step 3:  Request a Developer Key

README.md

@@ -179,6 +179,9 @@ If you do not provide a Vimeo API key, a warning log will be recorded in `config
 ### Google Analytics
 If you would like to use Google Analytics for tracking usage of UDOIT, create a new tracking code and add it to `config/localConfig.php` in the `define('GA_TRACKING_CODE', '');` statement.  For example, if your tracking code is `UA-12345678-1`, that line should look like `define('GA_TRACKING_CODE', 'UA-12345678-1');` when you're done.
 
+### Admin Panel
+As of 2.5.0, the admin panel is still an experimental feature.  Consider it a first draft of what we'd like it to be.  It lets you view reports across your institution, generate statistics about reports and user growth, and administer user accounts.  This feature is disabled by default.  To enable it, change `$admin_panel_enabled` to `true`.
+
 ### Installing the LTI in Canvas
 Log into Canvas to add UDOIT: