Manpage gpio(1): Regularise header

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

gpio/gpio.1

@@ -1,4 +1,4 @@
-.TH "GPIO" "January 2015" "Command-Line access to Raspberry Pi's GPIO"
+.TH gpio 1 "January 2015" wiringPi "Command-Line access to Raspberry Pi's GPIO"
 
 .SH NAME
 gpio \- Command-line access to Raspberry Pi's GPIO