Adding advice

Author: jsoref

.github/actions/spell-check/advice.txt

@@ -0,0 +1,11 @@
+If you run into a url form that you can't easily
+whitelist, consider adding a pattern into
+[.github/actions/spell-check/patterns.txt](.github/actions/spell-check/patterns.txt).
+
+If you have a file / directory / set of files
+that shouldn't be checked, please add them to
+[.github/actions/spell-check/excludes/excludes.txt](.github/actions/spell-check/excludes/excludes.txt).
+
+Otherwise, you can add whitelist entries to an
+appropriate file in:
+[.github/actions/spell-check/whitelist/](.github/actions/spell-check/whitelist/).