port using-easybuild page to MarkDown

[boegel]

This was a pretty big effort to port, so it deserves a careful review by a 2nd pair of eyes...

[orbsmiv]

@boegel I'll update this PR with the changes we've made to the internal linking system so that it's consistent with the other current PRs. I'll pop it on "draft" for now but please feel free to overrule if you want to get it merged and mop the links up later!

[boegel]

@boegel I'll update this PR with the changes we've made to the internal linking system so that it's consistent with the other current PRs. I'll pop it on "draft" for now but please feel free to overrule if you want to get it merged and mop the links up later!

Makes sense to me, thanks for the effort!

[orbsmiv]

@branfosj I've looked through the whole page and also checked each link. The autorefs links, (e.g. mkdocs_autorefs.plugin: using-easybuild.md: Could not find cross-reference target '[basic_usage_help]') refer to headers that will be in the auto-generated version_specific files. I've created an issue (c.f. #24) to log these as and when they crop-up, although I think that we should add a placeholder file to hold all of the link-names whilst the script to generated the actual content is being written.

changes made