README: add docs on running isort/black/pyright

This commit adds some additional instructions on using developer tools
to conform to project style checks in CI.

README.md

@@ -355,10 +355,25 @@ To run the tests:
 
     pytest
 
-To run CI checks locally:
+To run linting checks locally:
 
     pre-commit run --all-files
 
+Some of the pre-commit checks, like `isort` or `black`, will auto-fix
+the problems they find. So if the above command returns an error, try
+running it again, it might succeed the second time :)
+
+Running all the checks can be slow, so you can also run checks
+individually, e.g., to format source code that fails `isort` or `black`
+checks:
+
+    pre-commit run --all-files isort
+    pre-commit run --all-files black
+
+To diagnose why `pyright` checks are failing:
+
+    pre-commit run --all-files pyright
+
 ### The HTML renderer Vue.js app
 
 The HTML renderer works by embedding a JSON representation of the sample with