Update support URL links according to the following document

[bbondy]

https://docs.google.com/spreadsheets/d/16ubLUdPWmbzD4wiiiu0QbEGA6tbhJgqBemp_eVHz3FA/edit#gid=0

QA note:
Best effort if you can find some of the URLs described to make sure they go to the right place.
Don't spend too long but do verify some of them from the PR code.

[srirambv]

Verification Passed on

Brave	0.55.16 Chromium: 70.0.3538.54 (Official Build) (64-bit)
Revision	4f8e578b6680574714e9ed3bb9f02922b4dde40d-refs/branch-heads/3538@{#937}
OS	Linux

• Verified address bar link under Setting->Search pointed to the correct support link
• Verified Learn more for WebRTC pointed to the correct GitHub page link

Went through verification using the following build under macOS 10.13.6 x64 - PASSED

Brave	0.55.16 Chromium: 70.0.3538.54 (Official Build) (64-bit)
Revision	4f8e578b6680574714e9ed3bb9f02922b4dde40d-refs/branch-heads/3538@{#937}
OS	Mac OS X

• Verified that the address bar link under Setting->Search pointed to the correct support link
• Verified that the Learn more link under Do Not Track opened the correct support link
• Verified that the ? link under chrome://settings/passwords opened the correct support link
• Verified that the Learn more link under chrome://settings/resetProfileSettings?origin=userclick opened the correct support link

Verification Passed on

Brave	0.55.16 Chromium: 70.0.3538.54 (Official Build) (64-bit)
Revision	4f8e578b6680574714e9ed3bb9f02922b4dde40d-refs/branch-heads/3538@{#937}
OS	Windows

• Verified that the address bar link under Setting->Search pointed to the correct support link
• Verified that the Learn more link under Do Not Track opened the correct support link
• Verified that the ? link under chrome://settings/passwords opened the correct support link
• Verified that the Learn more link under chrome://settings/resetProfileSettings?origin=userclick opened the correct support link