docs: Prepare for new sub tree

See #11925

docs/content/en/functions/math/Sub.md

@@ -1,24 +0,0 @@
----
-title: math.Sub
-description: Subtracts one or more numbers from the first number. 
-categories: []
-keywords: []
-action:
-  aliases: [sub]
-  related:
-    - functions/math/Add
-    - functions/math/Div
-    - functions/math/Mul
-    - functions/math/Product
-    - functions/math/Sum
-  returnType: any
-  signatures: [math.Sub VALUE VALUE...]
----
-
-If one of the numbers is a [`float`], the result is a `float`.
-
-```go-html-template
-{{ sub 12 3 2 }} → 7
-```
-
-[`float`]: /getting-started/glossary/#float