Fix typo in S1171 (#3695)

rules/S1171/java/rule.adoc

@@ -1,6 +1,6 @@
 == Why is this an issue?
 
-Non-static initializers, also known as instance initializers, are blocks of code within a class that is executed when an instance of the
+Non-static initializers, also known as instance initializers, are blocks of code within a class that are executed when an instance of the
 class is created. They are executed when an object of the class is created just before the constructor is called.
 Non-static initializers are useful when you want to perform some common initialization logic for all objects of a class. They allow you to
 initialize instance variables in a concise and centralized manner, without having to repeat the same initialization code in each constructor.