Add more info and context to cert-manager documentation

[LappleApple]

What issue with the docs have you found?

• Missing information
• Incorrect information
• Something else

Describe what you are trying to do

Either:

• Guide a user to configure the WeGO dashboard using TLS with cert-manager and complete the journey: for example, request the certificate and show how everything works.
• Or, if we aim to just name that cert-manager is one of the ways to get that setup, then remove the part about installing cert-manager and potentially name other TLS providers like AWS Certificate Manager or Vault.

Which docs version are you using?

0.30.0

Which pages are affected?

• https://docs.gitops.weave.works/docs/configuration/tls/

Detail the issues you found and the improvements that you would like to see

https://docs.gitops.weave.works/docs/configuration/tls/ needs more info; see comment

Would you be able or interested to contribute this work to the docs?

Sure