Update imported docbooks cache,proxy,useragent,cookies,netpref,ebrowsing-webshortcuts,smb+trash

move into existing dir docs using subdir kcontrol5 to make make co-installable, adapt CMakeLists.txt, change dtd to kf5
rename ebrowsing to webshortcuts
reapply a few updates done in plasma-desktop
proofread, bump date + releaseinfo
REVIEW:128912