As verified with Martyn

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Merge done to enable documentation be be fixed, because of removal of
alias directive and addition of related algorithms directive.

Signed-off-by: Karl Palmen <karl.palmen@stfc.ac.uk>

Tidys up a few pages and links along the way.
Refs #22082

Refs #22082

Adds a brief explanation of the master pipeline view to the developer
documentation.

Refs #22082