Fix Reference Link for Declarative clients (#1323)

Author: pinalbaldha

aip/general/0009.md

@@ -111,7 +111,7 @@ Examples of clients include the following:
 - Libraries, such as an SDK for a particular programming language
 - Scripts that operates on a JSON representation of a resource after reading it
   from an API
-- Tools, such as a [Declarative client][]
+- Tools, such as a [Declarative clients][]
 - Visual UIs, such as a web application
 
 ### Google API