Improve documentation of soup_uri_normalize
Improve documentation of soup_uri_normalize

The docs do not mention anything about %-encoding, but that's part of
the normalization since 226f6382.

https://bugzilla.gnome.org/show_bug.cgi?id=761742

jwendell/libsoup,jwendell/libsoup,jwendell/libsoup,jwendell/libsoup,jwendell/libsoup