Description of problem:
The new UDN BGP docs have some inaccuracies and the structure of our docs causes some confusion between MelalLB BGP and UDN BGP.

• The examples' namespaces need to be fixed.

• Suggested restructure:1. About BGP - Theoretical introduction of the feature, without going too deep, basically without the session "5.1.2. Configuring the FRRConfiguration CRD".
  2. Enabling BGP
  3. Migrating FRR-K8s resources
  3. How to use it? -> Here is where the "Configuring the FRRConfiguration CRD" would be.

The same applies to Route advertisements section (move "6.1.2. RouteAdvertisements object configuration" and "6.1.3. Examples advertising pod IP addresses with BGP" to after "6.2. Enabling route advertisements").

I would also suggest moving Disabling BGP and Route advertisements to the end of each documentation.

Please coordinate this update with the Telco docs team. 

Version-Release number of selected component (if applicable):
4.20