Update activity_about.xml & correction of mising character

[gilardh]

• Add Twitter link

• Add Discord link

• Add website myhush.org link

• Add credits link

• Clean code

• Reduction of spaces between lines

• Make the page scrollable

• Formatting the 'About' page

• Correction of missing character in the zAddr and tAddr on 'Receive' screen #20

[gilardh]

[leto]

@gilardh thank you!!