Update docs/user_guide/authenticate.md

Fix typo - "login" to "log in"

Co-authored-by: Matt Fisher <[email protected]>

docs/user_guide/authenticate.md

@@ -1,6 +1,7 @@
 # Authentication
 
-You can use `earthaccess` to search for datasets and data without needing to login.  However, to access (download or stream) NASA Earth science data, whether from one of the NASA
+You can use `earthaccess` to search for datasets and data without needing to log in.
+However, to access (download or stream) NASA Earth science data, whether from one of the NASA
 Distributed Active Archive Centers (DAACs) or from NASA Earthdata Cloud, you need
 an Earthdata Login account.  You can register for a free Earthdata Login (EDL) account [here](https://urs.earthdata.nasa.gov/).