Update progress.phtml

[jonashrem]

links to magento dev docs are outdated. See https://community.magento.com/t5/Technical-Issues/Can-t-install-Magento-2-on-PHP-5-6-30/m-p/82895/highlight/false#M3749 for example

Description

Some of the links to magento devdocs are outdated. This PR fixes this within progress.phtml.

Fixed Issues (if relevant)

Manual testing scenarios

• install magento via website
• Test Error-Paths

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[mzeis]

Hi @jonashrem, thanks for your PR! I will probably process it after the holidays.

[mzeis]

Thanks again @jonashrem for providing this PR. For the records, this has been merged into 2.2-develop.