chore: fix update-docs workflow for forked PRs

[viviveevee]

Description

My update-docs.yml workflow breaks on PRs from forks (see #2490). Trying to fix this.

How Has This Been Tested?

According to this, the fix should work.

Checklist:

• The title of this PR complies with Conventional Commits.
• I have edited the CHANGELOG accordingly.
• I have made corresponding changes to the documentation.

[smallstepman]

LGTM! ✨

[smallstepman]

shall we try this out? :)

[viviveevee]

It's trying in #2490 as we speak :)

[smallstepman]

@sesi200 looks like it's working now :)

fyi, in #2490 PR there was a new button in GHA/workflows section at the bottom of conversation tab, and it was something along these lines:

First-time contributors cannot run workflow before approval. 
+--------------------+
|   Approve and run  |
+--------------------+

shame I didn't think about taking a screenshot, but it looked 👌

[viviveevee]

@smallstepman that had nothing to do with my changes, that's just something that appears on forks since they may contain malicious code