JP-3246 added link to top webpage to JWST helpdesk

[jemorrison]

Resolves JP-3246

Closes #

This PR adds a link to JWST help desk to the JWST pipeline line landing page.

Checklist for maintainers

• added entry in CHANGES.rst within the relevant release section
• updated or added relevant tests
• updated relevant documentation
• added relevant milestone
• added relevant label(s)
• ran regression tests, post a link to the Jenkins job below.
  How to run regression tests on a PR
• Make sure the JIRA ticket is resolved properly

[jemorrison]

@howard I followed how other topics are linked to pages in the top index.rst and added a
jwst/user_documentation/jwst_helpdesk.rst

If this is not how you want the help desk link added to top page let me know and I will change it/.

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (3866c80) 77.01% compared to head (f805ba8) 77.01%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #7610   +/-   ##
=======================================
  Coverage   77.01%   77.01%           
=======================================
  Files         456      456           
  Lines       36625    36625           
=======================================
  Hits        28208    28208           
  Misses       8417     8417           

Flag	Coverage Δ		*Carryforward flag
nightly	77.44% <ø> (ø)		Carriedforward from 3866c80

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[hbushouse]

I wonder if having this new entry tucked way down at the end of the list of top-level sections that can be clicked on will render it semi-invisible to most people. I think it would be more visible and easier to implement if we just added the text (as its own short paragraph) right after the opening "Welcome to the ..." paragraph at the top of the main RTD page. So you wouldn't need the extra .rst files for that.

[hbushouse]

Looks good. The updated doc page builds correctly and the link is active.