message: Update configuration.md
  Clarify what the magic string is
diff: @@ -15,7 +15,7 @@ desired when authoring and processing instructions.
  The Literate configuration file is a CommonMark (aka Markdown) file that has code blocks.
  -In order that AutoRest identifies a CommonMark document as a **AutoRest Configuration** file, the markdown must contain the following string exactly (and not as the first line in the file!) :
  +In order that AutoRest identifies a CommonMark document as a **AutoRest Configuration** file, the markdown must contain the following string (we call it the magic string) exactly (and not as the first line in the file!) :
  ``` markdown
  > see https://aka.ms/autorest
  