remove obsolete crs_reference.md

[tuminoid]

Remove obsolete crs_reference.md.

Based on #447 (comment) and checking the content, it is indeed obsolete.

Fixes #446

[tuminoid]

/cc @adilGhaffarDev @lentzi90

[metal3-io-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kashifest

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [kashifest]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[tuminoid]

/hold
for thinking about #499 (comment)

[lentzi90]

/lgtm
The data is still there in the git history if we ever need it. Better to delete it from main to avoid confusion with the no-longer-existing APIs.

[tuminoid]

/lgtm The data is still there in the git history if we ever need it. Better to delete it from main to avoid confusion with the no-longer-existing APIs.

That is true.
/unhold

I've created #501 to create new documentation on CRs with images.