add --locked to cargo install instructions to avoid deps issues

docs/knowledgebase/integrate/subkey.md

@@ -22,7 +22,7 @@ install the dependencies and Subkey, respectively:
 
 ```bash
 $ curl https://getsubstrate.io -sSf | bash -s -- --fast
-$ cargo install --force subkey --git https://github.com/paritytech/substrate --version 2.0.0
+$ cargo install --force subkey --git https://github.com/paritytech/substrate --version 2.0.0 --locked
 ```
 
 ### Compiling with Cargo

docs/tutorials/start-a-private-network/keygen.md

@@ -15,7 +15,7 @@ Subkey is a tool that generates keys specifically designed to be used with Subst
 Begin by compiling and installing the utility. This may take up to 15 minutes or so.
 
 ```bash
-cargo install --force subkey --git https://github.com/paritytech/substrate --version 2.0.0
+cargo install --force subkey --git https://github.com/paritytech/substrate --version 2.0.0 --locked
 ```
 
 We will need to generate at least **2** keys from each type. Every node will need to have its own