Various small miscellaneous fixes

* Fixes #15294 - BoolToStringConverter should not check if falseValue or trueValue is empty
* Fixes #15266 - Small typo in resource file
* Fixes #14037 - XML comments for DbContext.Attach unclear
* Fixes #14001 - DbSet.Local does not automatically call DetectChanges
* Fixes #13210 - WithExtension suggests that 'this' is updated, as well as returning 'this'

src/EFCore.Design/Properties/DesignStrings.resx

@@ -1,17 +1,17 @@
 <?xml version="1.0" encoding="utf-8"?>
 <root>
-  <!-- 
-    Microsoft ResX Schema 
-    
+  <!--
+    Microsoft ResX Schema
+
     Version 2.0
-    
-    The primary goals of this format is to allow a simple XML format 
-    that is mostly human readable. The generation and parsing of the 
-    various data types are done through the TypeConverter classes 
+
+    The primary goals of this format is to allow a simple XML format
+    that is mostly human readable. The generation and parsing of the
+    various data types are done through the TypeConverter classes
     associated with the data types.
-    
+
     Example:
-    
+
     ... ado.net/XML headers & schema ...
     <resheader name="resmimetype">text/microsoft-resx</resheader>
     <resheader name="version">2.0</resheader>
@@ -26,36 +26,36 @@
         <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
         <comment>This is a comment</comment>
     </data>
-                
-    There are any number of "resheader" rows that contain simple 
+
+    There are any number of "resheader" rows that contain simple
     name/value pairs.
-    
-    Each data row contains a name, and value. The row also contains a 
-    type or mimetype. Type corresponds to a .NET class that support 
-    text/value conversion through the TypeConverter architecture. 
-    Classes that don't support this are serialized and stored with the 
+
+    Each data row contains a name, and value. The row also contains a
+    type or mimetype. Type corresponds to a .NET class that support
+    text/value conversion through the TypeConverter architecture.
+    Classes that don't support this are serialized and stored with the
     mimetype set.
-    
-    The mimetype is used for serialized objects, and tells the 
-    ResXResourceReader how to depersist the object. This is currently not 
+
+    The mimetype is used for serialized objects, and tells the
+    ResXResourceReader how to depersist the object. This is currently not
     extensible. For a given mimetype the value must be set accordingly:
-    
-    Note - application/x-microsoft.net.object.binary.base64 is the format 
-    that the ResXResourceWriter will generate, however the reader can 
+
+    Note - application/x-microsoft.net.object.binary.base64 is the format
+    that the ResXResourceWriter will generate, however the reader can
     read any of the formats listed below.
-    
+
     mimetype: application/x-microsoft.net.object.binary.base64
-    value   : The object must be serialized with 
+    value   : The object must be serialized with
             : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
             : and then encoded with base64 encoding.
-    
+
     mimetype: application/x-microsoft.net.object.soap.base64
-    value   : The object must be serialized with 
+    value   : The object must be serialized with
             : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
             : and then encoded with base64 encoding.
 
     mimetype: application/x-microsoft.net.object.bytearray.base64
-    value   : The object must be serialized into a byte array 
+    value   : The object must be serialized into a byte array
             : using a System.ComponentModel.TypeConverter
             : and then encoded with base64 encoding.
     -->
@@ -358,6 +358,6 @@ Change your target project to the migrations project by using the Package Manage
     <value>No static method 'CreateHostBuilder(string[])' was found on class 'Program'.</value>
   </data>
   <data name="UsingHostingServices" xml:space="preserve">
-    <value>Using applicaiton service provider from Microsoft.Extensions.Hosting.</value>
+    <value>Using application service provider from Microsoft.Extensions.Hosting.</value>
   </data>
 </root>

src/EFCore/DbContextOptions.cs

@@ -63,11 +63,12 @@ public virtual TExtension GetExtension<TExtension>()
         }
 
         /// <summary>
-        ///     Adds the given extension to the options.
+        ///     Adds the given extension to the underlying options and creates a new
+        ///     <see cref="DbContextOptions"/> with the extension added.
         /// </summary>
         /// <typeparam name="TExtension"> The type of extension to be added. </typeparam>
         /// <param name="extension"> The extension to be added. </param>
-        /// <returns> The same options instance so that multiple calls can be chained. </returns>
+        /// <returns> The new options instance with the given extension added. </returns>
         public abstract DbContextOptions WithExtension<TExtension>([NotNull] TExtension extension)
             where TExtension : class, IDbContextOptionsExtension;
 

src/EFCore/DbContextOptions`.cs

@@ -42,11 +42,12 @@ public DbContextOptions(
         }
 
         /// <summary>
-        ///     Adds the given extension to the options.
+        ///     Adds the given extension to the underlying options and creates a new
+        ///     <see cref="DbContextOptions"/> with the extension added.
         /// </summary>
         /// <typeparam name="TExtension"> The type of extension to be added. </typeparam>
         /// <param name="extension"> The extension to be added. </param>
-        /// <returns> The same options instance so that multiple calls can be chained. </returns>
+        /// <returns> The new options instance with the given extension added. </returns>
         public override DbContextOptions WithExtension<TExtension>(TExtension extension)
         {
             Check.NotNull(extension, nameof(extension));