Restructure query-languages docs files for clarity (#124797)

In a few previous PR's we restructured the ES|QL docs to make it possible to generate them dynamically.

This PR just moves a few files around to make the query languages docs easier to work with, and a little more organized like the ES|QL docs.

A bit part of this was setting up redirects to the new locations, so other repo's could correctly link to the elasticsearch docs.

docs/reference/query-languages/sql/sql-operators-math.md

@@ -0,0 +1,51 @@
+---
+mapped_pages:
+  - https://www.elastic.co/guide/en/elasticsearch/reference/current/sql-operators-math.html
+---
+
+# Math Operators [sql-operators-math]
+
+Perform mathematical operations affecting one or two values. The result is a value of numeric type.
+
+## `Add (+)` [sql-operators-plus]
+
+```sql
+SELECT 1 + 1 AS x;
+```
+
+
+## `Subtract (infix -)` [sql-operators-subtract]
+
+```sql
+SELECT 1 - 1 AS x;
+```
+
+
+## `Negate (unary -)` [sql-operators-negate]
+
+```sql
+SELECT - 1 AS x;
+```
+
+
+## `Multiply (*)` [sql-operators-multiply]
+
+```sql
+SELECT 2 * 3 AS x;
+```
+
+
+## `Divide (/)` [sql-operators-divide]
+
+```sql
+SELECT 6 / 3 AS x;
+```
+
+
+## `Modulo or Remainder(%)` [sql-operators-remainder]
+
+```sql
+SELECT 5 % 2 AS x;
+```
+
+