remove outdated note about declared eth_call being experimental (#1014)

Author: 0xa3k5

website/src/pages/en/subgraphs/developing/creating/advanced.mdx

@@ -456,8 +456,6 @@ In this configuration:
 
 ## Declared eth_call
 
-> Note: This is an experimental feature that is not currently available in a stable Graph Node release yet. You can only use it in Subgraph Studio or your self-hosted node.
-
 Declarative `eth_calls` are a valuable Subgraph feature that allows `eth_calls` to be executed ahead of time, enabling `graph-node` to execute them in parallel.
 
 This feature does the following: