x11vnc, xdotool, rev: add pages (#1264)

pages/common/rev.md

@@ -0,0 +1,11 @@
+# rev
+
+> Reverse a line of text.
+
+- Reverse the text string "hello":
+
+`echo "hello" | rev`
+
+- Reverse an entire file and print to stdout:
+
+`rev {{file}}`