Update documentation on reservoir simulators

[berland]

Explicitly state how NUM_CPU should be handled for Eclispe and Flow.

Fix backslash rendering bug for multiline Ert config examples

Fix erroneous example on supplying multiple options to Eclipse 100. Curly braces do not work.

Issue
Resolves gruff

Approach
🧠 ✍🏻

• PR title captures the intent of the changes, and is fitting for release notes.
• Added appropriate release note label
• Commit history is consistent and clean, in line with the contribution guidelines.
• Make sure unit tests pass locally after every commit (git rebase -i main --exec 'just rapid-tests')

When applicable

• When screenshots are changed: Review screenshot-PR in ert-testdata,
  merge screenshot-PR in ert-testdata before merging this PR.
• When there are user facing changes: Updated documentation
• New behavior or changes to existing untested code: Ensured that unit tests are added (See Ground Rules).
• Large PR: Prepare changes in small commits for more convenient review
• Bug fix: Add regression test for the bug
• Bug fix: Add backport label to latest release (format: 'backport release-branch-name')

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.74%. Comparing base (bf96534) to head (b5e20c0).
⚠️ Report is 8 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #14318      +/-   ##
==========================================
- Coverage   91.92%   91.74%   -0.19%     
==========================================
  Files         485      485              
  Lines       33655    34708    +1053     
==========================================
+ Hits        30939    31844     +905     
- Misses       2716     2864     +148     

Flag	Coverage Δ
cli-tests	35.70% <ø> (-0.84%)	⬇️
fuzz	43.89% <ø> (-0.48%)	⬇️
gui-tests	58.17% <ø> (-0.46%)	⬇️
performance-and-unit-tests	81.04% <ø> (+0.09%)	⬆️
test	45.28% <ø> (-0.63%)	⬇️

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

Files with missing lines	Coverage Δ
...lugins/hook_implementations/forward_model_steps.py	94.59% <ø> (ø)

... and 14 files with indirect coverage changes

[Copilot]

Pull request overview

Updates the forward model step documentation strings for reservoir simulators, aiming to clarify CPU handling (NUM_CPU vs parsing PARALLEL) and to correct/clarify configuration examples shown in generated docs.

Changes:

• Expanded Eclipse 100 / Eclipse 300 documentation to explain how CPU count is determined via PARALLEL vs NUM_CPU.
• Updated examples to fix multiline backslash rendering and to show multiple <OPTS> passed as a space-separated string (not curly braces).
• Expanded Flow documentation to describe CPU selection behavior and forwarding multiple options via <OPTS>.

Suppressed comments (2)

src/ert/plugins/hook_implementations/forward_model_steps.py:320

• Minor wording/grammar: use “set up” (verb) rather than “setup” in the description text.

Ert will parse the DATA-file for the :code:`PARALLEL` keyword and setup the
correct number of CPUs. If the :code:`PARALLEL` keyword is setup/computed
during the forward model, then :code:`NUM_CPU` must be set in the Ert config
for correct configuration of CPU usage.

src/ert/plugins/hook_implementations/forward_model_steps.py:397

• Capitalization/terminology: “CPU” is typically uppercased in this context ("per CPU core").

returns. An appropriate setting for the threads parameter (per cpu core)

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[codspeed-hq]

Merging this PR will not alter performance

✅ 36 untouched benchmarks

---

_{Comparing berland:update_ressim_docs (b5e20c0) with main (4e36dd4)}

[oyvindeide]

Suggest linking to the DATA_FILE-keyword, as that is needed for us to parse it to read PARALLEL, same for ecl100.

[berland]

fixed!

[ertomatic]

Screenshots differ from baselines. A baseline update PR has been prepared: equinor/ert-testdata#113

[berland]

Screenshots differ from baselines. A baseline update PR has been prepared: equinor/ert-testdata#113

False positive due to missing merge in equinor/ert-testdata#106