docs: clarify ty.toml comment for suppressed diagnostics

The suppressed rules are for incomplete type stubs, not missing ones.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ty.toml

@@ -2,7 +2,7 @@
 python-version = "3.12"
 
 [rules]
-# Third-party libraries without type stubs
+# Third-party libraries with missing or incomplete type stubs
 unresolved-import = "warn"
 unresolved-attribute = "warn"
 call-non-callable = "warn"