Edit User Guide to match updates in ConcertAddressBook

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Files with missing lines	Coverage Δ	Complexity Δ
src/main/java/seedu/address/ui/HelpWindow.java	0.00% <ø> (ø)	0.00 <0.00> (ø)

... and 22 files with indirect coverage changes