Align page title with summary title

Aside from aligning it with the summary entry, another reason to say
"never type fallback change" is that if we were to say "to itself", we
should say "never type fall back to itself", grammatically.  But it
seems better here to just use the noun form, so we'll be consistent
with that.

Author: traviscross

src/rust-2024/never-type-fallback.md

@@ -1,4 +1,4 @@
-# Never type fallback to itself
+# Never type fallback change
 
 🚧 The 2024 Edition has not yet been released and hence this section is still "under construction".