note stability of clean_names and fix a double space

NEWS.md

@@ -3,7 +3,7 @@
 ## Release summary
 A stable version 1.0.0, with a new `tabyl` API and with breaking changes to the output of `clean_names()`.
 
-This builds on the original functionality of janitor, with similar-but-improved tools and  significantly-changed implementation.
+This builds on the original functionality of janitor, with similar-but-improved tools and significantly-changed implementation.
 
 ## Breaking changes
 
@@ -21,6 +21,8 @@ These changes may cause old code to break. E.g., a raw column name `variableName
 
 To minimize this inconvenience, there's a quick fix for compatibility: you can find-and-replace to insert the argument `case = "old_janitor"`, preserving the old behavior of `clean_names()` as of janitor version 0.3.1 (and thus not have to redo your scripts beyond that.)
 
+No further changes are planned to `clean_names()` and its results should be stable from version 1.0.0 onward.
+
 ## Major Features
 
 - `clean_names()` transliterates accented letters, e.g., `çãüœ` becomes `cauoe` [(#120)](https://github.com/sfirke/janitor/issues/120).  Thanks to **@fernandovmacedo**.