Documentation - clean up small typos and whitespace issues

- some files had zero-width spaces
- fix one typo
- fix formatting / line breaks in some markdown

docs/contributing/index.md

@@ -4,7 +4,7 @@
 
 The easiest way to contribute to Wagtail is to tell us how to improve it! First, check to see if your bug or feature request has already been submitted at [github.com/wagtail/wagtail/issues](https://github.com/wagtail/wagtail/issues). If it has, and you have some supporting information which may help us deal with it, comment on the existing issue. If not, please [create a new one](https://github.com/wagtail/wagtail/issues/new), providing as much relevant context as possible. For example, if you're experiencing problems with installation, detail your environment and the steps you've already taken. If something isn't displaying correctly, tell us what browser you're using, and include a screenshot if possible.
 
-If your bug report is a security issue, **do not** report it with an issue. Please read our ​guide to [reporting security issues](security).
+If your bug report is a security issue, **do not** report it with an issue. Please read our guide to [reporting security issues](security).
 
 ```{toctree}
 :maxdepth: 2

docs/releases/2.15.rst

@@ -67,7 +67,7 @@ Individual fixes were implemented by a large number of first-time and seasoned c
  * Update tab styles so the active tab can be identified (Dmitrii Faiazov, LB (Ben Johnston))
  * Make hamburger menu a button for tab and high contrast accessibility (Amy Chan, Dan Braghis)
  * Tag fields now have the correct background (Desai Akshata, LB (Ben Johnston))
- * Added sidebar vertical seperation with main content (Onkar Apte, LB (Ben Johnston))
+ * Added sidebar vertical separation with main content (Onkar Apte, LB (Ben Johnston))
  * Added vertical separation between field panels (Chakita Muttaraju, LB (Ben Johnston))
  * Switch widgets on/off states are now visually distinguishable (Sakshi Uppoor, Thibaud Colas)
  * Checkbox widgets on/off states are now visually distinguishable (Thibaud Colas, Jacob Topp-Mugglestone, LB (Ben Johnston))

docs/support.md

@@ -28,7 +28,7 @@ Our [Github discussion boards](https://github.com/wagtail/wagtail/discussions) a
 
 If you think you've found a bug in Wagtail, or you'd like to suggest a new feature, please check the current list at [github.com/wagtail/wagtail/issues](https://github.com/wagtail/wagtail/issues). If your bug or suggestion isn't there, raise a new issue, providing as much relevant context as possible.
 
-If your bug report is a security issue, **do not** report it with an issue. Please read our ​guide to [reporting security issues](../contributing/security).
+If your bug report is a security issue, **do not** report it with an issue. Please read our guide to [reporting security issues](../contributing/security).
 
 ## Torchbox