docs: remove contribution requirements from skill guidance

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: MariusStorhaug

.github/plugin/psmodule/skills/psmodule-skill-authoring/SKILL.md

@@ -19,8 +19,7 @@ guidance.
   only the skill's trigger, agent operating sequence, handoff/report contract,
   and stop conditions in `SKILL.md`.
 - Preserve the plugin's scope and make adjacent work a separate change.
-- Open a draft PR early, use small commits, include the required Copilot
-  co-author trailer, and report the PR URL, files, validation, decisions, and
-  blockers to the owning session.
+- Open a draft PR early, use small commits, and report the PR URL, files,
+  validation, decisions, and blockers to the owning session.
 - Stop and report instead of guessing when the skill boundary, source-of-truth
   document, plugin ownership, or validation requirement is unclear.

docs/content/guides/writing-plugin-skills.md

@@ -64,14 +64,7 @@ agents, define the parent owner, child boundary, expected handoff, validation,
 report-back, and stop conditions. Do not silently broaden a skill into
 unrelated repository work.
 
-## Contribution and validation
-
-Work on a dedicated branch, open a draft pull request early, and use small
-commits. Include the required co-author trailer in every commit:
-
-```text
-Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
-```
+## Validation
 
 Run the smallest existing checks that cover the changed surfaces: