docs: clarify that cache.ttl is set once and document workaround for per-request TTL changes (#1209)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: arthurfiorette <47537704+arthurfiorette@users.noreply.github.com>

Author: Copilot

docs/src/config/request-specifics.md

@@ -130,6 +130,13 @@ the interpreter can't determine their TTL value to override this one.
 
 :::
 
+::: warning
+
+The `ttl` is only applied when the response is **first cached**; changing it on follow-up
+requests has no effect. See [#1024](https://github.com/arthurfiorette/axios-cache-interceptor/issues/1024) for workarounds.
+
+:::
+
 The time until the cached value is expired in milliseconds.
 
 If a function is used, it will receive the complete response and waits to return a TTL