CompatHelper: bump compat for "Documenter" to "1.0" for package docs

[github-actions[bot]]

This pull request changes the compat entry for the Documenter package from ~0.26, 0.27 to ~0.26, 0.27, 1.0 for package docs.

This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry. It is your responsibility to make sure that your package tests pass before you merge this pull request.

[coveralls]

Pull Request Test Coverage Report for Build 6204245175

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 97.452%

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Totals
Change from base Build 5607270936:	0.0%
Covered Lines:	2027
Relevant Lines:	2080

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💛 - Coveralls