HM-456: Fix RTD(readthedocs) generation of central node

1. What this MR does / why we need it:

• Fix the rtd generation link
• Update readthedocs.yaml file
• Temporary link to the docs: https://ska-tmc-centralnode-hm456.readthedocs.io/en/latest/

2. Make sure that you've checked the boxes below before you submit MR:

• No conflict with master branch.
• Merge Request Title appropriate.
• Unit/Integration tests added and existing test cases are passing.
• Variable and Function names state the purpose.
• There is no commented out code, print/debug statements.
• Logs are added wherever necessary.
• Exception is handled wherever required.