Document %a = %a, %b and %a ,= %b (and link ,= to that section for convenience)

[AlexDaniel]

I grepped the docs and couldn't fine any place where we show something like this:

my %a = :11a, :22b;
%a = %a, :33x;
say %a # OUTPUT: «{a => 11, b => 22, x => 33}␤»

Also, this can be written using ,=:

my %a = :11a, :22b;
%a ,= :33x;
say %a # OUTPUT: «{a => 11, b => 22, x => 33}␤»

,= is of course not specific to hashes and behaves like any other op combined with =. However, it seems like ,= is particularly useful for hashes, and people who stumble upon it in code should be able to find this section quickly.

[cfa]

It might be worth adding examples using the hash contextualiser too,

say %(%a, :33x);  # OUTPUT: «{a => 11, b => 22, x => 33}␤»
say  (%a, :33x);  # OUTPUT: «({a => 11, b => 22} x => 33)␤»