examples: more descriptions

docs/examples/curlgtk.c

docs/examples/curlx.c

docs/examples/evhiperfifo.c

docs/examples/externalsocket.c

docs/examples/fileupload.c

docs/examples/fopen.c

docs/examples/ftp-wildcard.c

docs/examples/ftpget.c

docs/examples/ftpgetinfo.c

docs/examples/ftpgetresp.c

docs/examples/ftpsget.c

docs/examples/ftpupload.c

docs/examples/ftpuploadresume.c

docs/examples/getinfo.c

docs/examples/getinmemory.c

docs/examples/ghiper.c

docs/examples/hiperfifo.c

docs/examples/href_extractor.c

docs/examples/htmltidy.c