update xss.md, web-based-attacks-and-owasp.md, wlan.md and others

[andreluis-oliveira]

update xss.md

• new content

update privilege-escalation.md

• new link

update core-concepts-of-zero-trust.md

• new link

update zero-day.md

• new content
• Note: This second zero-day topic is a subset of the "Attack Types and Differences" topic, so the content is minimal compared to the zero-day%40zqRaMmqcLfx400kJ-h0LO.md

update wifi.md -new video link

update wlan.md

• new video links ( professor messer )

update vpn.md

• new links

update web-based-attacks-and-owasp.md

• new links