caller: add page (#15246)

pages/common/caller.md

@@ -0,0 +1,16 @@
+# caller
+
+> Print function context.
+> More information: <https://www.gnu.org/software/bash/manual/bash.html#index-caller>.
+
+- Print the line and filename where the current function was called:
+
+`caller`
+
+- Print the line, function and filename where the current function was called:
+
+`caller 0`
+
+- Print the line, the function name and the filename of a function call `n` frames back:
+
+`caller {{n}}`