README: add demo

Author: wilsonehusin

README.md

@@ -2,6 +2,8 @@
 
 SQLDoc is a markdown documentation for SQL tables. Inspired by Rails ActiveRecord `schema.rb` and [drwl/annotaterb](https://github.com/drwl/annotaterb).
 
+![Demo of SQLDoc](demo/demo.gif)
+
 ## Why?
 
 Projects often manages their schema roll out through migrations (e.g. [golang-migrate/migrate](https://github.com/golang-migrate/migrate)). As a project matures, it's quite common to encounter several `ALTER TABLE` commands, which makes it difficult to have a near-instant idea of what the schema looks like.

demo/demo.gif

@@ -0,0 +1,39 @@
+Output demo/demo.gif
+
+Set FontSize 12
+Set Width 900
+Set Height 900
+
+Type "sqldoc help"
+Sleep 500ms
+Enter
+Sleep 3s
+
+Hide
+Type "clear"
+Enter
+Show
+
+Type "sqldoc init"
+Sleep 500ms
+Enter
+
+Type "bat sqldoc.yaml"
+Sleep 500ms
+Enter
+Sleep 5s
+
+Hide
+Type "clear"
+Enter
+Show
+
+Type "sqldoc"
+Sleep 500ms
+Enter
+Sleep 5s
+
+Type "bat schema.md"
+Sleep 500ms
+Enter
+Sleep 5s