Update systemd.mdx

Author: shekohex

pages/docs/node/systemd.mdx

@@ -203,7 +203,7 @@ rustup target add wasm32-unknown-unknown --toolchain nightly
         To ensure you have successfully generated the keys correctly run:
 
         ```sh filename="ls" copy
-        ls ~/data/validator/<USERNAME>/chains/tangle-testnet/keystore/
+        ls <BASE_PATH>/chains/tangle-testnet/keystore/
         # You should see a some file(s) there, these are the keys.
         ```