Adding clamp and friends to function index in documentation (elastic#137863)

* Adding clamp docs

* Update docs/reference/query-languages/esql/_snippets/lists/conditional-functions-and-expressions.md

Co-authored-by: Kostas Krikellas <[email protected]>

* Update docs/reference/query-languages/esql/_snippets/lists/conditional-functions-and-expressions.md

Co-authored-by: Kostas Krikellas <[email protected]>

* Update docs/reference/query-languages/esql/_snippets/lists/conditional-functions-and-expressions.md

Co-authored-by: Kostas Krikellas <[email protected]>

* comments

---------

Co-authored-by: Kostas Krikellas <[email protected]>

Author: pabloem

docs/reference/query-languages/esql/_snippets/functions/description/clamp.md

@@ -2,3 +2,7 @@
 * [`COALESCE`](../../functions-operators/conditional-functions-and-expressions.md#esql-coalesce)
 * [`GREATEST`](../../functions-operators/conditional-functions-and-expressions.md#esql-greatest)
 * [`LEAST`](../../functions-operators/conditional-functions-and-expressions.md#esql-least)
+* [`CLAMP`](../../functions-operators/conditional-functions-and-expressions.md#esql-clamp) {applies_to}`stack: preview 9.3` {applies_to}`serverless: preview`
+* [`CLAMP_MIN`](../../functions-operators/conditional-functions-and-expressions.md#esql-clamp_min) {applies_to}`stack: preview 9.3` {applies_to}`serverless: preview`
+* [`CLAMP_MAX`](../../functions-operators/conditional-functions-and-expressions.md#esql-clamp_max) {applies_to}`stack: preview 9.3` {applies_to}`serverless: preview`
+

docs/reference/query-languages/esql/_snippets/functions/description/clamp_max.md

@@ -28,3 +28,9 @@ Conditional functions return one of their arguments by evaluating in an if-else
 :::{include} ../_snippets/functions/layout/least.md
 :::
 
+:::{include} ../_snippets/functions/layout/clamp.md
+:::
+:::{include} ../_snippets/functions/layout/clamp_min.md
+:::
+:::{include} ../_snippets/functions/layout/clamp_max.md
+:::