Update hostname in new api keys docs as well

Author: krivard

docs/api/api_keys.md

@@ -44,21 +44,21 @@ there are several ways to use your key to authenticate your requests:
 The request parameter “api_key” can be used to pass the API key to the server.
 Example:
 
-    http://delphi.cmu.edu/epidata/covidcast/meta?api_key=your_api_key_here
+    https://api.delphi.cmu.edu/epidata/covidcast/meta?api_key=your_api_key_here
 
 ### Via Basic Authentication
 
 Another method is using the HTTP basic authorization header with the username
 "epidata" and the API key as the password. Example:
 
 ```
-curl -u 'epidata:your_api_key_here' https://delphi.cmu.edu/epidata/covidcast/meta
+curl -u 'epidata:your_api_key_here' https://api.delphi.cmu.edu/epidata/covidcast/meta
 ```
 
 ### Via Bearer Token
 
 Another method is providing the key in a bearer token header. Example:
 
 ```
-curl -H 'Authorization: Bearer your_api_key_here' https://delphi.cmu.edu/epidata/covidcast/meta
+curl -H 'Authorization: Bearer your_api_key_here' https://api.delphi.cmu.edu/epidata/covidcast/meta
 ```