shift: add page (#5415)

pages/common/shift.md

@@ -0,0 +1,12 @@
+# shift
+
+> Bash built-in command that shifts the arguments passed to the calling function or script by a specified number of places.
+> More information: <https://www.gnu.org/software/bash/manual/bash.html#index-shift>.
+
+- Move arguments by one place dropping the first argument:
+
+`shift`
+
+- Move arguments by N places dropping the first N arguments:
+
+`shift {{N}}`