some documentation fixes (partial):

- search&replace: "e.g." -> "⪚"
- search&replace: "etc" -> "&etc;"
- search&replace: "sub window" -> "sub-window"
- and some other minor fixes...

not (yet) included from original patch author:
- URL changes from http to https
- wording change "directory" -> "folder"
- misleading text in description of the "menu" command