v17: Update key

Update the key docs now that we worked out that a bunch of RPC methods
are either deprecated or do not return anything.

We choose not to implement deprecated for v17 because v17.1 is so far
back anyways. And obviously if nothing is returned we don't need a type
for it.

Author: tcharding

json/src/v17/mod.rs

@@ -8,9 +8,10 @@
 //! in the `model` module are version non-specific and are strongly typed using `rust-bitcoin`.
 //!
 //! Key:
-//! - `[ ]` means not yet done.
-//! - `[x]` marks means implemented _and_ tested.
-//! - `[-]` means it was considered and intentionally not done.
+//! - `[ ]` Not yet done.
+//! - `[x]` Implemented _and_ tested.
+//! - `[-]` Intentionally not done, typically because method does not return anything, returns
+//!         a single integer, or is deprecated.
 //!
 //! **== Blockchain ==**
 //! - [x] `getbestblockhash`