doc: remove "note that" from writing-tests.md

Refs: nodejs/remark-preset-lint-node#16

PR-URL: #28329
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

doc/guides/writing-tests.md

@@ -390,7 +390,7 @@ Next add the test to the `sources` in the `cctest` target in node.gyp:
 ],
 ```
 
-Note that the only sources that should be included in the cctest target are
+The only sources that should be included in the cctest target are
 actual test or helper source files. There might be a need to include specific
 object files that are compiled by the `node` target and this can be done by
 adding them to the `libraries` section in the cctest target.