Update installation documentation to include Cython instructions

[mrmundt]

Fixes #3204

Summary/Motivation:

Bill pointed out that there is no documentation for how to install with Cythonization enabled. This adds a section to the installation page.

Changes proposed in this PR:

• Update installation page to add Cython instructions
• Fix some stuff on the installation page that annoyed me

Legal Acknowledgement

By contributing to this software project, I have read the contribution guide and agree to the following terms and conditions for my contribution:

1. I agree my contributions are submitted under the BSD license.
2. I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

[mrmundt]

Preview of changed page: https://pyomo--3208.org.readthedocs.build/en/3208/installation.html#installation-with-cython

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.39%. Comparing base (c849905) to head (399cbf5).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3208      +/-   ##
==========================================
- Coverage   88.40%   88.39%   -0.01%     
==========================================
  Files         846      846              
  Lines       95156    95156              
==========================================
- Hits        84118    84109       -9     
- Misses      11038    11047       +9     

Flag	Coverage Δ
linux	86.33% <ø> (ø)
osx	76.17% <ø> (ø)
other	86.52% <ø> (-0.02%)	⬇️
win	83.82% <ø> (-0.02%)	⬇️

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