Chore: (Docss) Minor tweaks around SB env vars

[jonniebigodes]

With this pull request, issue #18082 is closed.

What was done:

• Updated Env vars docs to include information that vars are built into SB
• Updated FAQ to reflect that
• Updated the fields table in the configure/overview

[nx-cloud]

☁️ Nx Cloud Report

CI is running/has finished running commands for commit 17b8bf4. As they complete they will appear below. Click to see the status, the terminal output, and the build insights.

📂 See all runs for this branch

---

✅ Successfully ran 1 target

• nx run-many --target=prepare --all --parallel=2 --max-parallel=15 -- --optimized

---

Sent with 💌 from NxCloud.

[codecov]

Codecov Report

Merging #18418 (17b8bf4) into next (6b8210b) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             next   #18418   +/-   ##
=======================================
  Coverage   32.04%   32.04%           
=======================================
  Files         975      975           
  Lines       19216    19216           
  Branches     4031     4031           
=======================================
  Hits         6158     6158           
+ Misses      12495    12494    -1     
- Partials      563      564    +1     

Impacted Files	Coverage Δ
addons/a11y/src/components/A11YPanel.tsx	84.09% <0.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6b8210b...17b8bf4. Read the comment docs.