linkcheckbroken fails on README.rst files

[stevepiercy]

Links of affected pages in Plone Documentation, if any.

• https://github.com/collective/collective.exportimport
• https://github.com/zopefoundation/z3c.form/tree/master/src/z3c/form/browser

Description

linkcheckbroken currently fails due to a recent change in GitHub. It is a regression that they should fix.

There is an open discussion in GitHub Community.

@pbauer mentioned that he created a ticket as well.

This issue is merely a placeholder until GitHub can deploy a fix. If it goes on for a long time, we could update the two links to the raw README files instead.

[stevepiercy]

Reopened to remind me to revert the linkcheck timeout from 10 seconds back to 5.