Revert "Initial docs for file-based catalogs"

[camilamacedo86]

Reverts #177

@joelanford @anik120 @jmccormick2001, @timflannagan

We need to revert this one. We need to find a way to start to add the docs for DC without removing the current docs.
Until the CSV be supported we cannot remove the docs

[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: camilamacedo86
To complete the pull request process, please assign marc-obrien after the PR has been reviewed.
You can assign the PR to them by writing /assign @marc-obrien in a comment when ready.

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

Needs approval from an approver in each of these files:

• OWNERS

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

[anik120]

Reverting is not the solution here.
I just cut a new release for v0.18.z #185
So https://v0-18-z.olm.operatorframework.io/ has all the information about sqllite backed Catalogs (it's basically the main branch minus @joelanford's PR that adds the DC docs)

We'll need to add a migration doc in the main branch for operator/catalog authors moving to the new format. All docs that touch upon the format will have links to the old format in the v0.18.z release.

A best practices doc for operator/catalog authors in adopting the new plaintext backed Catalogs is also under works right at this moment. Stay tuned.