docs: fix link to API explorer (#760)

diff --git a/docs/start.md b/docs/start.md
index feebe35..4caf706 100644
--- a/docs/start.md
+++ b/docs/start.md
@@ -128,7 +128,7 @@
 
 ## Finding information about the APIs
 
-Use the [APIs Explorer](http://developers.google.com/api-client-library/python/reference/apis_explorer) to browse APIs, list available methods, and even try API calls from your browser.
+Use the [APIs Explorer](https://developers.google.com/apis-explorer/) to browse APIs, list available methods, and even try API calls from your browser.
 
 ## Library reference documentation