build: a better kit-building link

Author: nedbat

howto.txt

@@ -45,7 +45,7 @@
         $ make publish
 - Kits:
     - Manually trigger the kit GitHub Action
-        - https://github.com/nedbat/coveragepy/actions?query=workflow%3A%22Build+kits%22
+        - https://github.com/nedbat/coveragepy/actions/workflows/kit.yml
     - Download and check built kits from GitHub Actions:
         $ make clean download_kits check_kits
     - examine the dist directory, and remove anything that looks malformed.