Update vignettes/pull-nhsn.Rmd

vignettes/pull-nhsn.Rmd

@@ -21,7 +21,7 @@ We will use the [Socrata Open Data API (SODA)](https://dev.socrata.com/) API end
 
 
 ## API Key
-First, you'll want to go to [data.cdc.gov](https://data.cdc.gov/) and request an API token. This is not strictly required, but it is generally considered polite, and it will speed up your data requests (the polite get served first!).
+First, you'll want to go to [`data.cdc.gov`](https://data.cdc.gov/) and request an API token. This is not strictly required, but it is generally considered polite, and it will speed up your data requests (the polite get served first!).
 
 To request a token, navigate to [`data.cdc.gov`'s developer settings page](https://data.cdc.gov/profile/edit/developer_settings). You will be prompted to log in. If you have CDC credentials, you can use those. Otherwise, you can [sign up for an account](https://data.cdc.gov/signup) with Tyler Data and Insights (the contractor that manages `data.cdc.gov`). Once logged in, navigate to the [developer settings page](https://data.cdc.gov/profile/edit/developer_settings), click the "Create new API key" button and follow the prompts.