docs: Add general use citation from IRIS-HEP Strategic Plan

[matthewfeickert]

Description

Add general citation from IRIS-HEP Strategic Plan for the Next Phase of Software Upgrades for HL-LHC Physics.

Checklist Before Requesting Reviewer

• Tests are passing
• "WIP" removed from the title of the pull request
• Selected an Assignee for the PR to be responsible for the log summary

Before Merging

For the PR Assignees:

• Summarize commit messages into a comprehensive review of the PR

* Add general citation from 'IRIS-HEP Strategic Plan for the Next
  Phase of Software Upgrades for HL-LHC Physics'.
   - c.f. https://inspirehep.net/literature/2628983

[codecov]

Codecov Report

Base: 98.30% // Head: 98.30% // No change to project coverage 👍

Coverage data is based on head (9e75e04) compared to base (98ae036).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2107   +/-   ##
=======================================
  Coverage   98.30%   98.30%           
=======================================
  Files          69       69           
  Lines        4531     4531           
  Branches      645      645           
=======================================
  Hits         4454     4454           
  Misses         45       45           
  Partials       32       32           

Flag	Coverage Δ
contrib	97.88% <ø> (ø)
doctest	61.15% <ø> (ø)
unittests-3.10	96.31% <ø> (ø)
unittests-3.8	96.33% <ø> (ø)
unittests-3.9	96.35% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[matthewfeickert]

Relevant RTD build: https://pyhf--2107.org.readthedocs.build/en/2107/citations.html#general-citations

[matthewfeickert]

I'm going to approve and merge this myself. As always, PRs approved by a single core dev can be reverted as needed by the rest of the dev team.