Update release notes for v0.15.1 (#105)

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

RELEASE_NOTES.md

@@ -2,16 +2,12 @@
 
 ## Summary
 
-<!-- Here goes a general summary of what this release is about -->
+This is a bugfix release that mainly uses more up to date dependencies and extend the range of supported dependencies.  There is technically one breaking change though, but this is hardly used by anyone.
 
 ## Upgrading
 
 * `FileWatcher` no longer accepts or sets `None` as the `event_types` argument. Instead, all available event types are now set by default while still providing the flexibility to customize the event types as needed.
 
-## New Features
-
-<!-- Here goes the main new features and examples or instructions on how to use them -->
-
 ## Bug Fixes
 
-<!-- Here goes notable bug fixes that are worth a special mention or explanation -->
+* Many documentation examples were fixed.