Update supplementary docs

Author: JimBobSquarePants

articles/fonts/gettingstarted.md

@@ -1,8 +1,5 @@
 # Getting Started
 
->[!WARNING]
->Fonts is still considered BETA quality and we still reserve the rights to change the API shapes.
-
 >[!NOTE]
 >The official guide assumes intermediate level knowledge of C# and .NET. If you are totally new to .NET development, it might not be the best idea to jump right into a framework as your first step - grasp the basics then come back. Prior experience with other languages and frameworks helps, but is not required.
 
@@ -54,6 +51,6 @@ if(collection.TryFind("Emoji Font Name", out FontFamily emojiFamily))
         FallbackFontFamilies  = new [] { emojiFamily }
     };
 
-    FontRectangle rect = TextMeasurer.Measure("Text to measure", options);
+    FontRectangle rect = TextMeasurer.MeasureAdvance("Text to measure", options);
 }
 ```

articles/fonts/index.md

@@ -1,12 +1,9 @@
 # Introduction
 
->[!WARNING]
->Fonts is still considered BETA quality and we still reserve the rights to change the API shapes.
-
 ### What is Fonts?
 Fonts is a font loading and layout library built primarily to provide text drawing support to ImageSharp.Drawing.
 
-Built against [.NET Standard 1.3](https://docs.microsoft.com/en-us/dotnet/standard/net-standard), Fonts can be used in device, cloud, and embedded/IoT scenarios.  
+Built against [.NET Standard 2.0](https://docs.microsoft.com/en-us/dotnet/standard/net-standard), Fonts can be used in device, cloud, and embedded/IoT scenarios.  
 
 ### License  
 Fonts is licensed under under the terms of [Apache License, Version 2.0](https://opensource.org/licenses/Apache-2.0). Commercial support licensing options are available in addition to this license, see https://sixlabors.com/pricing for details.