docs: add in a note about [no cancel]

Author: ckipp01

docs/_docs/contributing/sending-in-a-pr.md

@@ -114,6 +114,15 @@ Below are commonly used ones:
 | `[skip community_build_a]`| Skip the "a" community build    |
 | `[skip docs]`             | Skip the scaladoc tests         |
 
+#### Making sure every commit triggers a new run
+
+By default the Dotty CI will cancel your previous runs if you push a new commit.
+This helps make sure the CI keeps moving without getting stuck running a ton of
+jobs if you push multiple times in a row. _However_, there are times you may
+want to run every commit. To do this, make sure your PR body contains `[no
+cancel]`. This will ensure that there are no cancellations of your previous
+runs.
+
 ### 7: Create your PR!
 
 When the feature or fix is completed you should open a [Pull