Fixing misspelled command

"guardrails" had an extra d

Author: jayercule

docs/hub/getting_started.md

@@ -21,7 +21,7 @@ guardrails configure
 You can download a guardrail from the Hub using the `install` command. For example, to download the `regex_match` guardrail, you can run:
 
 ```bash
-gudardrails hub install hub://guardrails/regex_match
+guardrails hub install hub://guardrails/regex_match
 ```
 
 ## 4. Use the Guardrail
@@ -70,4 +70,4 @@ guard = Guard().use(
 )
 
 guard.validate("My favorite phone is BlackBerry.")  # Guardrail Passes
-```
+```