Adds canvas clog function (#96418)

* Add canvas `clog` function in the doc

* Add basic example to the `clog` canvcas function

* clog canvas function: switch definition/purpose

Co-authored-by: Laurent HUET <[email protected]>

docs/canvas/canvas-function-reference.asciidoc

@@ -376,6 +376,37 @@ Clears the _context_, and returns `null`.
 *Returns:* `null`
 
 
+[float]
+[[clog_fn]]
+=== `clog`
+
+It outputs the _context_ in the console. This function is for debug purpose.
+
+*Expression syntax*
+[source,js]
+----
+clog
+----
+
+*Code example*
+[source,text]
+----
+filters
+  | demodata
+  | clog 
+  | filterrows fn={getCell "age" | gt 70}
+  | clog 
+  | pointseries x="time" y="mean(price)"
+  | plot defaultStyle={seriesStyle lines=1 fill=1}
+  | render
+----
+This prints the `datatable` objects in the browser console before and after the `filterrows` function.
+
+*Accepts:* `any`
+
+*Returns:* `any`
+
+
 [float]
 [[columns_fn]]
 === `columns`