Cleanup stray accountNonce reference (#1880)

* Cleanup stray accountNonce reference

* Comment for system.account upgrades

Author: jacogr

docs/start/FAQ.md

@@ -36,6 +36,8 @@ The length for this transaction validity is set to 50 blocks, which translates t
 
 ## My chain does not support system.account queries
 
-The API always tracks the latest Substrate master in terms of examples. This means that nonce & balance queries are done via the `api.query.system.account(<account>)` which returns a Tuple `(Index, AccountData)` where the first is the nonce, the second a struct containing the free and reserved balances. As with all `api.query.*` endpoint, this is decorated based on what the chain you connect to support.
+The API always tracks the latest Substrate master in terms of examples. This means that nonce & balance queries are done via the `api.query.system.account(<account>)` which returns a Tuple `(Index, AccountData)` where the first is the nonce, the second a struct containing the free and reserved balances. As with all `api.query.*` endpoints, this is decorated based on what the chain you connect to support, via the metadata exchange.
 
 It is possible that you are connecting to an older chain that has not been upgraded yet. For these chains, this storage entry won't be available (yet). To query the nonce on older chains, you can do a query to `api.query.system.accountNonce(<account>)` and balances can be retrieved via `api.query.balances.freeBalance(<account>)`.
+
+Likewise, if your chain has been upgraded recently and you are still using the old `system.accountNonce` or `balances.freeBalance` queries in your code (which is now not available in the chain metadata), you need to update it to query the new location.

docs/start/api.tx.md

@@ -28,7 +28,7 @@ The result for this call (we will deal with subscriptions in a short while), is
 
 Despite the single-line format of `signAndSend`, there is a lot happening under the hood (and all of this can be manually provided) -
 
-- Based on the sender, the API will retrieve the `system.accountNonce` to determine the next nonce to use
+- Based on the sender, the API will query `system.account` (or `system.accountNonce` on older chains) to determine the next nonce to use
 - The API will retrieve the current block hash and use it to create a mortal transaction, i.e. the transaction will only be valid for a limited number of blocks (by default this is 5 mins at 6s block times)
 - It will construct a payload and sign this, this includes the `genesisHash`, the `blockHash` for the start of the mortal era as well as the current chain `specVersion`
 - The transaction is submitted to the node