docs: don't hardcode main branch to a specific version in SKILL.md

Assisted-by: OpenCode

Author: zdrapela

skills/prow-trigger-nightly/SKILL.md

@@ -98,16 +98,13 @@ Constraint: `--image-repo` requires `--tag`, but `--tag` works on its own.
 
 ### Follow-up based on selections
 
-**If 2 or 3 selected (quay.io registry)** — fetch available tags and present as numbered options. Derive `--tag-filter` from the branch selected in Step 1 (strip `release-` prefix; for `main`, use the current development version):
+**If 2 or 3 selected (quay.io registry)** — fetch available tags and present as numbered options. For `release-*` branches, derive `--tag-filter` by stripping the `release-` prefix. For `main`, omit `--tag-filter` to show all available versions:
 
 ```bash
 # For release-1.10 branch:
 uv run scripts/trigger_nightly_job.py --list-tags --tag-filter 1.10
 
-# For main branch (currently maps to 1.11):
-uv run scripts/trigger_nightly_job.py --list-tags --tag-filter 1.11
-
-# Browse all versions (no filter):
+# For main branch (show all versions):
 uv run scripts/trigger_nightly_job.py --list-tags
 ```