[mkgmap-dev] Minor documentation update

Hi Gerd, now that my previous documentation patch has been committed, I have noticed a couple of errors in it that I didn't notice because I didn't have the means to compile it into the web pages. Please find attached a small patch that corrects these errors and adds some information on the input files, primarily to describe typ file compilation. I have also slightly tweaked the code for generating the options file from options.txt, but as the previous version does not appear to be in SVN, this has come across as a complete file, rather than the change (which is just the deletion of the hyphen character in 'if (line.startsWith(";-")) {'). Regards, Mike