Improve documentation

[chinyeungli]

Fixes
#2980 Added note on recommended process number for optimal performance
#2562 Enhance description of the --from-json option
Removed duplicate content from "All Available Options"

Tasks

• Reviewed contribution guidelines
• PR is descriptively titled 📑 and links the original issue above 🔗
• [] Tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR
  Run tests locally to check for errors.
• Commits are in uniquely-named feature branch and has no merge conflicts 📁
• Updated documentation pages (if applicable)
• Updated CHANGELOG.rst (if applicable)

The failing tests don't related to the documentation update.

Signed-off-by: Chin Yeung Li tli@nexb.com

[AyanSinhaMahapatra]

Thanks @chinyeungli looks good.
See my comments for your consideration

[AyanSinhaMahapatra]

@chinyeungli this was merged as default with #4104
See also docs above which was changed:

[Default: (number of CPUs)-1]

This explanation is nice, but we need to modify this a bit.
We could also say it's safer to use (number of CPUs)-2 for local machines with other applications (browser/IDEs/chatrooms etc) open, or even less after looking at current CPU usage.

We should probably have a seperate section on performance and explanations, but this can be done a bit more explicitly as a sub-task of #4069 eith detailed explanations and recommendations on CPU/memory

[AyanSinhaMahapatra]

I'm not sure we want to remove these sections, they are pretty useful IMHO

[chinyeungli]

@AyanSinhaMahapatra I'm removing this from the list-options since extract.rst is already included in other-commands.rst. Having it in both places seem redundant.

[AyanSinhaMahapatra]

Suggested change

	You can also convert the input .json file to other output format
	You can also convert the input ``.json`` file to other output format

[AyanSinhaMahapatra]

Generally the post-scan options (like --summary, --todo) are configured to just operate on the codebase (with top-level licenses/packages etc and all resource level results) and this should work fine with --from-json
The core scan options (like --license --info) and pre-scan options cannot be run here. There are some post-scan options which have required options as dependencies, so those also need to be there in the loaded scan if those options are being specified.

[chinyeungli]

@AyanSinhaMahapatra I am wondering is it true that all the "Pre-Scan" options cannot be run with --from-json?
https://scancode-toolkit.readthedocs.io/en/latest/cli-reference/list-options.html#all-pre-scan-options
It seems to be the "--ignore" and "--include" don't really need the code files to have it work (I didn't look at the source code to verify it). Also, https://scancode-toolkit.readthedocs.io/en/latest/cli-reference/core-options.html#from-json-option , the current --from-json` is usung --classify`` as a sample.

For the post-scans, I want to verify that if an option's dependencies are missing, the command still executes without errors, it just won’t return results related to the missing dependencies, correct?