Correction (when necessary) of the infix operator syntax

[Ariel Otilibili]

Is your feature request related to a problem? Please describe.
Following a discussion with @RaimoNiskanen, I am proposing to correct (when necessary) the syntax of infix operators in comments & documentation.

Describe the solution you'd like
A consistent quoting is expected; for instance, instead of ==/2 as here, it should be '=='/2.

Additional context

• 'and'/2
• 'or'/2
• 'xor'/2
• 'not'/1
• '>'/2
• '>='/2
• '<'/2
• '=<'/2
• '=:='/2 (#8645)
• '=='/2 (#8645)
• '=/='/2
• '/='/2
• '+'/2
• '-'/2
• '*'/2
• '/'/2
• 'div'/2
• 'rem'/2
• 'bor'/2
• 'band'/2
• 'bxor'/2
• 'bsl'/2
• 'bsr'/2
• 'bnot'/1
• '-'/1
• '+'/1
• '+'/2

[Ariel Otilibili]

As it is, the documented syntax is more legible than the proposal.