CLI usage text unification

[AliceInHunterland]

Sometimes we have -o file [-s start] and sometimes it --wif <wif> [--name <account_name>].
#3495 (comment)

[AnnaShaleva]

I vote for option with <> since it allows to clearly identify flag example and multi-words flags look more recognizable with <>.

[roman-khimov]

https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html

Also

       SYNOPSIS      A brief summary of the command or function's interface.

                     For  commands, this shows the syntax of the command and its arguments (including options); boldface is used for as-is text and italics are used to indicate replaceable arguments.  Brackets ([]) surround optional arguments, vertical bars (|) separate choices, and ellipses (...) can be repeated.  For functions, it shows any required data declarations
                     or #include directives, followed by the function declaration.