Update src/stabilization_guide.md

Co-Authored-By: rajcspsg <[email protected]>

Author: mark-i-m

src/stabilization_guide.md

@@ -157,7 +157,7 @@ becomes
 
 If any documentation for this feature exists, it should be
 in the `Unstable Book`, located at `src/doc/unstable-book`.
-Regardless of its existence, the page for the feature gate
+If it exists, the page for the feature gate
 should be removed.
 
 If there was documentation there, integrating it into the