In the effort of repairing broken links as per QTBUG-96127,
a series of RFC links referring to `tools.ietf.org/html/*` were modified
to point to the new address that the site redirected to.
To simplify executing a similar task and to diminish the duplication of
manually inserted urls, the already existing `rfc.qdoc` file, containing
`\externalpage` commands directing to RFC locations, was enhanced with
links to all RFCs that were mentioned in the current documentation, so
as to aggregate this common category of links.
All links pointing to a `ietf` domain inside QDoc documentation blocks
were then changed to use the newly provided external-references.
Task-number: QTBUG-96127
Pick-to: 6.2
Change-Id: I2a52eb6aa8c9e346f64ef1a627b039220d9f6c2a
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
10eedd175e