Add a missing question mark in the FAQ

Author: johananl

semver.md

@@ -286,7 +286,7 @@ modification depends on whether you updated your dependencies in order to fix
 a bug or introduce new functionality. I would usually expect additional code
 for the latter instance, in which case it's obviously a minor level increment.
 
-### What if I inadvertently alter the public API in a way that is not compliant with the version number change (i.e. the code incorrectly introduces a major breaking change in a patch release)
+### What if I inadvertently alter the public API in a way that is not compliant with the version number change (i.e. the code incorrectly introduces a major breaking change in a patch release)?
 
 Use your best judgment. If you have a huge audience that will be drastically
 impacted by changing the behavior back to what the public API intended, then