Minor doc fixes: missing types, missing debug options

Chase down some types, add missing `{log,N}` debug option.

I did not make any changes to source code, but there are problems there as well.

In the source code itself there are a few places where `log_to_file` is mistakenly identified as `logfile`:

````
gen.erl:45:                    | {'logfile', string()}.
gen.erl:60:%%      Flag = trace | log | {logfile, File} | statistics | debug
gen_fsm.erl:172:%%%      Flag ::= trace | log | {logfile, File} | statistics | debug
gen_server.erl:149:%%%      Flag ::= trace | log | {logfile, File} | statistics | debug
````

Also, the `install` and `{log,N}` tuples are mostly missing from the source code. Details at https://gist.github.com/macintux/7852089