improved the sentence to make it clear for entering admin in both the username and password (#76141)

* improved the sentence to make it clear for entering admin in both the username and password

* Update docs/sources/getting-started/build-first-dashboard.md

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Co-authored-by: Christopher Moyer <35463610+chri2547@users.noreply.github.com>

docs/sources/getting-started/build-first-dashboard.md

@@ -32,7 +32,7 @@ To sign in to Grafana for the first time:
 
    The default HTTP port that Grafana listens to is `3000` unless you have configured a different port.
 
-1. On the sign-in page, enter `admin` for the username and password.
+1. On the sign-in page, enter `admin` for both the username and password.
 1. Click **Sign in**.
 
    If successful, you will see a prompt to change the password.