Update doc.

Author: jcs090218

README.md

@@ -93,9 +93,13 @@ insertion. In this example, `(docstr--c-style-search-string 2)` is the
 string base on the `search-string` information. Then this is the result.
 
 <p align="center">
-<img src="./etc/csharp-vs-doc-demo.gif" width="450" height="172"/>
+  <img src="./etc/csharp-vs-doc-demo.gif" width="450" height="172"/>
 </p>
 
+## Before Insertion
+
+You can customize document before you actually insert anything.
+
 ## Configure Faces
 
 This package provides a way to customize the document string faces in a