Remove substrate-compat default feature flag (#1078)

* remove defautl feature, add target cfg, change CI job waml

* adjust CI job

* Adjust docs

* adjust the CI job

* add wasm targe to ci again

* remove the unresolved links from the book

* Update subxt/src/book/usage/transactions.rs

---------

Co-authored-by: James Wilson <james@jsdw.me>

subxt/src/tx/signer.rs

@@ -50,7 +50,7 @@ mod pair_signer {
     where
         T: Config,
         Pair: PairT,
-        // We go via an sp_runtime::MultiSignature. We can probably generalise this
+        // We go via an `sp_runtime::MultiSignature`. We can probably generalise this
         // by implementing some of these traits on our built-in MultiSignature and then
         // requiring them on all T::Signatures, to avoid any go-between.
         <SpMultiSignature as Verify>::Signer: From<Pair::Public>,