Revise security guidelines for XSS and CSR

[titoBouzout]

Reordered recommendations for XSS protection and added clarification on CSRF attacks.

• I have read the Contribution guide
• This PR references an issue (except for typos, broken links, or other minor problems)

Description(required)

1. It reorders items on the security page
2. add note about using or constructing urls via user input
3. Notes headers can be forged

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