Update functions.mdx

Text says "Header Transforms," but it works on Rewrite URL, which is also considered a Transform, and is also listed on a page hyperlinked to. Removing "Header" since it works on all Transforms.

Author: cf-scott

src/content/docs/ruleset-engine/rules-language/functions.mdx

@@ -122,7 +122,7 @@ Decodes a Base64-encoded String specified in `source`.
 For example, with the following HTTP request header: `client_id: MTIzYWJj`, `(any(decode_base64(http.request.headers["client_id"][*])[*] eq "123abc"))` would return `true`.
 
 :::note
-You can only use the `decode_base64()` function in [header transform rules](/rules/transform/), [custom rules](/waf/custom-rules/), and [rate limiting rules](/waf/rate-limiting-rules/).
+You can only use the `decode_base64()` function in [transform rules](/rules/transform/), [custom rules](/waf/custom-rules/), and [rate limiting rules](/waf/rate-limiting-rules/).
 :::
 
 ### `ends_with`