Fixed some typos

Author: vweijsters

StyleCop.Analyzers/StyleCop.Analyzers/ReadabilityRules/SA1135UsingDirectivesMustBeQualified.cs

@@ -63,7 +63,7 @@ private static void HandleUsingDeclaration(SyntaxNodeAnalysisContext context)
 
         private static void CheckUsingDeclaration(SyntaxNodeAnalysisContext context, UsingDirectiveSyntax usingDirective)
         {
-            // Usings outside of a namepsace are always qualified.
+            // Usings outside of a namespace are always qualified.
             if (usingDirective.Parent is NamespaceDeclarationSyntax && usingDirective.StaticKeyword.IsKind(SyntaxKind.None))
             {
                 string usingString = usingDirective.Name.ToString();

documentation/SA1135.md

@@ -26,7 +26,7 @@ A using directive is not qualified.
 For example, the following code would produce a violation of this rule:
 
 ```csharp
-namepsace System.Threading
+namespace System.Threading
 {
     using IO;
     using Tasks;
@@ -36,7 +36,7 @@ namepsace System.Threading
 The following code would not produce any violations:
 
 ```csharp
-namepsace System.Threading
+namespace System.Threading
 {
     using System.IO;
     using System.Threading.Tasks;
@@ -45,12 +45,12 @@ namepsace System.Threading
 
 ## How to fix violations
 
-To fix a violation of this rule, use the full qualified namepsace name.
+To fix a violation of this rule, use the full qualified namespace name.
 
 ## How to suppress violations
 
 ```csharp
-namepsace N1.N2
+namespace N1.N2
 {
 #pragma warning disable SA1135 // Using directives must be qualified
     using N3;