PRs to main now

CONTRIBUTING.md

@@ -14,7 +14,7 @@ A good description helps us to review and understand your proposed changes. For
 
 ### Target branch for pull requests
 
-Please make all PRs against the `0_15` branch.
+Please make all PRs against the `main` branch.
 
 ### Updating your code
 While the PR is open - and under review by maintainers - you may be asked to modify your PR source code.
@@ -105,4 +105,4 @@ Good:
 
 There is no hard character limit for a comment within a line,
 though as a rule of thumb consider wrapping after 120 characters.
-Inline comments are OK if they describe that line only and are not exceedingly wide.
+Inline comments are OK if they describe that line only and are not exceedingly wide.