fswebcam: fix typo in device name (#1837)

pages/common/fswebcam.md

@@ -10,7 +10,7 @@
 
 `fswebcam -r {{width}}x{{height}} {{filename}}`
 
-- Take a picture from selected device(Default is /dev/vidoe0):
+- Take a picture from selected device(Default is /dev/video0):
 
 `fswebcam -d {{device}} {{filename}}`