Docs missing information about OSS licenses vs proprietary

[nwneisen]

Copied over from BOP ticket: https://mirantis.jira.com/browse/BOP-1806

Raise as tech bug as it probably needs someone to help dig out all the licenses and then pass them to docs team to document.

We have prospects asking for a doc that specifies all the licenses for each component in MKE4. Specifically they are looking to see which parts are proprietary to Mirantis.

In MKE3 we have something like https://docs.mirantis.com/mke/3.7/oss-download.html so it looks like we need something similar for MKE4.