Add note about "atomic units" to dev guides

knowledge-base/developer-guides/daemon-rpc.md

@@ -15,6 +15,8 @@ This is a list of the bitmonerod daemon RPC calls, their inputs and outputs, and
 
 Many RPC calls use the daemon's JSON RPC interface while others use their own interfaces, as demonstrated below.
 
+Note: In the following guide, "atomic units" refer to the smallest fraction of 1 Monero according to the bitmonerod and simplewallet implementation. **1 XMR = 1e12 atomic units.**
+
 ### [JSON RPC Methods](#json-rpc-methods):
 
 * [getblockcount](#getblockcount)

knowledge-base/developer-guides/wallet-rpc.md

@@ -24,6 +24,7 @@ All simplewallet methods use the same JSON RPC interface. For example:
         -d '{"jsonrpc":"2.0","id":"0","method":"'$METHOD'","params":'"$PARAMS"'}' \
         -H 'Content-Type: application/json'
 
+Note: In the following guide, "atomic units" refer to the smallest fraction of 1 Monero according to the bitmonerod and simplewallet implementation. **1 XMR = 1e12 atomic units.**
 
 ### Index of JSON RPC Methods: