Update docs edit pencil icon link for 2.x docs

[discdiver]

Update docs edit pencil icon link for 2.x docs to 2.x branch.

Closes #14374

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Checklist

• [x] This pull request includes a label categorizing the change e.g. maintenance, fix, feature, enhancement, docs.
• [x] This pull request references any related issue by including "closes <link to issue>"
  • If no issue exists and your change is not a small fix, please create an issue first.
• [ ] If this pull request adds new functionality, it includes unit tests that cover the changes
• [ ] If this pull request removes docs files, it includes redirect settings in mint.json.
• [ ] If this pull request adds functions or classes, it includes helpful docstrings.