say "certain"

Author: BoxyUwU

src/doc/rustc-dev-guide/src/tests/compiletest.md

@@ -90,7 +90,7 @@ The following test suites are available, with links for more information:
 | `rustdoc-ui`                         | Check terminal output of `rustdoc` ([see also](ui.md))                   |
 
 Some rustdoc-specific tests can also be found in `ui/rustdoc/`.
-These tests ensure that lints that are emitted as part of executing rustdoc
+These tests ensure that certain lints that are emitted as part of executing rustdoc
 are also run when executing rustc.
 Run-make tests pertaining to rustdoc are typically named `run-make/rustdoc-*/`.