docs: add npx blurb

src/pages/stacks-blockchain/accounts.md

@@ -87,7 +87,7 @@ const stacksAddress = getAddressFromPrivateKey(
 A second alternative would be to use [stacks-gen](https://github.com/psq/stacks-gen).  This tool will generate all the keys you need in one place, including the values needed for calling the stacking contract, and also a WIF key for use with `bitcoind`.
 
 #### stacks-gen prerequisite
-Install `npx` if not already installed.
+Install [npx](https://github.com/npm/npx) if not already installed.  (npx will check whether <command> exists in $PATH, or in the local project binaries, and execute that. If <command> is not found, it will be installed prior to execution).
 ```
 npm install -g npx
 ```