Adds thank you message (#4989)

* Adds thank you message

* Update CHANGELOG.md

Fix line length

Author: BoDonkey

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Adds
 
 * Implemented GET /api/v1/@apostrophecms/login/whoami route such that it returns the details of the currently logged in user; added the route to the login module.
+  Thanks to [sombitganguly](https://github.com/sombitganguly) for this contribution.
 * Adds keyboard shortcuts for manipulating widgets in areas. Includes Cut, Copy, Paste, Delete, and Duplicate.
 * Adds dynamic choices working with piece manager filters. 
 * Allow `import.imageTags` (array of image tag IDs) to be passed to the rich text widget when importing (see https://docs.apostrophecms.org/reference/api/rich-text.html#importing-inline-images).