Align the directories linted in CI with the defaults in scripts-dev/lint.sh (#9191)

The lists of source directories to lint between `tox.ini` and `lint.sh` became out of sync. This PR tightens them up and adds some comments reminding any future readers to keep the list in sync.

changelog.d/9191.misc

@@ -0,0 +1 @@
+Add some missing source directories to the automatic linting script.

scripts-dev/lint.sh

@@ -80,7 +80,8 @@ else
   # then lint everything!
   if [[ -z ${files+x} ]]; then
     # Lint all source code files and directories
-    files=("synapse" "tests" "scripts-dev" "scripts" "contrib" "synctl" "setup.py" "synmark")
+    # Note: this list aims the mirror the one in tox.ini
+    files=("synapse" "docker" "tests" "scripts-dev" "scripts" "contrib" "synctl" "setup.py" "synmark" "stubs" ".buildkite")
   fi
 fi
 

tox.ini

@@ -24,7 +24,8 @@ deps =
     # install the "enum34" dependency of cryptography.
     pip>=10
 
-# directories/files we run the linters on
+# directories/files we run the linters on.
+# if you update this list, make sure to do the same in scripts-dev/lint.sh
 lint_targets =
     setup.py
     synapse