Modify rule S4035: Fix typo in 'Why is this an issue' section - "IEqu…

…itable<T>" -> "IEquatable<T>" (#3535)

Co-authored-by: Scott Moore <scott.moore@viavisolutions.com>

rules/S4035/csharp/rule.adoc

@@ -6,7 +6,7 @@ When a class implements the `IEquatable<T>` interface, it enters a contract that
 Alternatively `IEqualityComparer<T>` provides a safer interface and is used by collections or `Equals` could be made `virtual`.
 
 
-This rule raises an issue when an unsealed, `public` or `protected` class implements `IEquitable<T>` and the `Equals` is neither `virtual` nor `abstract`.
+This rule raises an issue when an unsealed, `public` or `protected` class implements `IEquatable<T>` and the `Equals` is neither `virtual` nor `abstract`.
 
 
 === Noncompliant code example