GHA vulnerabilities documentation improvements

[moe-ad]

Description of the modifications

Created so @clatapie comments on #639 can be tracked/worked on.
Action items:

• Section title Addressing common vulnerabilities in python libraries and applications should be corrected (python --> Python)
• For every remediation example, provide more information about the vulnerability (this one might be a bit of redundancy if added, because shouldn't zizmor audit rules documentation be the main reference?)
• Tips should be made more apparent in sections where they appear

Useful links and references

No response

[clatapie]

I understand your point regarding the possible redundancy with zizmore documentation but, IMO, it would make the documentation more self-explanatory.
Also, it can be done with one sentence at the top of the example or with comments directly added on the code as it was done within the addressing common vulnerabitilies section.