docs: OpenEBS 4.5 Docs

[balaharish7]

Create the OpenEBS 4.5 documentation branch from the current main documentation branch.
Update the OpenEBS version references in the following documents:

• Installation Guide
• Upgrade Guide

Update the versions.json file to include the new OpenEBS 4.5 version.
Update the version-specific sidebar file:

• Replace version references in all sidebar id entries with the OpenEBS 4.5 version.