Update ca2249.md and fix typo in the example code (#45842)

Author: bforget163

docs/fundamentals/code-analysis/quality-rules/ca2249.md

@@ -110,22 +110,22 @@ class MyClass
         found = str.Contains('x');
 
         // No comparisonType in string overload, adds StringComparison.CurrentCulture to resulting fix
-        found = !string.Contains("text", StringComparison.CurrentCulture);
-        found = string.Contains("text", StringComparison.CurrentCulture);
+        found = !str.Contains("text", StringComparison.CurrentCulture);
+        found = str.Contains("text", StringComparison.CurrentCulture);
 
         // comparisonType equal to StringComparison.Ordinal, removes the argument
-        found = !string.Contains('x');
-        found = string.Contains('x');
+        found = !str.Contains('x');
+        found = str.Contains('x');
 
-        found = !string.Contains("text");
-        found = string.Contains("text");
+        found = !str.Contains("text");
+        found = str.Contains("text");
 
         // comparisonType different than StringComparison.Ordinal, preserves the argument
-        ;found = !string.Contains('x', StringComparison.OrdinalIgnoreCase)
-        found = string.Contains('x', StringComparison.CurrentCulture);
+        found = !str.Contains('x', StringComparison.OrdinalIgnoreCase);
+        found = str.Contains('x', StringComparison.CurrentCulture);
 
-        found = !string.Contains("text", StringComparison.InvariantCultureIgnoreCase);
-        found = string.Contains("text", StringComparison.InvariantCulture);
+        found = !str.Contains("text", StringComparison.InvariantCultureIgnoreCase);
+        found = str.Contains("text", StringComparison.InvariantCulture);
 
         // This case had to be manually fixed
         if (!str.Contains("text"))