Information on excluded files in README has a broken link

[StevenMaude]

This URL — https://github.com/wpengine/site-deploy/blob/main/exclude.txt is broken in the README:

github-action-wpe-site-deploy/README.md

Line 122 in 3ce4a3d

* This action excludes several files and directories from the deploy by default. See the [exclude.txt](https://github.com/wpengine/site-deploy/blob/main/exclude.txt) for reference.