managen: correct the warning for un-escaped '<' and '>'

[bagder]

1. make sure the check is done before the backticks are replaced

2. ignore less-than and greater-than used within backticks

(adjust proxy.md that now showed a two-space warning)

[andrei-korshikov]

Thank you! 42960eb breaks --write-out manual completely—i.e. in 8.12.1 the whole --write-out section is replaced with symbol 3. And now it is generated correctly again;)