Update docs links for monodocs

[neverett]

Why are the changes needed?

Once we sunset the old docs, redirects from the old flytesnacks, flytectl, and flyteidl docs links to the new monodocs links will stop working, so we need to update the old links in all external sites.

What changes were proposed in this pull request?

Updated docs links. I did a search and replace for old links, but also tested changes manually, since some old links were 404ing.

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Related PRs

TBD

Docs link

TBD

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (1cd775a) 58.92% compared to head (d1443ab) 58.92%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4834   +/-   ##
=======================================
  Coverage   58.92%   58.92%           
=======================================
  Files         645      645           
  Lines       55380    55380           
=======================================
  Hits        32632    32632           
  Misses      20165    20165           
  Partials     2583     2583           

Flag	Coverage Δ
unittests	58.92% <ø> (ø)

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