Docs: update README files & docs to reflect RC status

[dreamorosi]

Description of the improvement

Summary of the proposal

With the first RC release the project has completed the developer preview phase, we need to update the README and the documentation to reflect it.

How, where did you look for information
README files of each utility, main one, documentation pages.

Missing or unclear documentation

N/A

Improvement

Specify we are now in the RC phase and link to the announcement.

Related existing documentation

N/A

Related issues, RFCs

N/A

[github-actions]

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