update readme for features

Author: zbryikt

README.md

@@ -1,7 +1,14 @@
 # @plotdb/sheet
 
-simple sheet ui in vanilla JS.
-
+simple sheet UI in vanilla JS. Features:
+
+ - fast, infinite scrolling.
+ - small - < 20KB when minimized
+ - vanilla - only optional depends on Papaparse
+ - CSS-based layout - better user experience
+ - size of column/row auto fit content yet still customizable
+ - support frozen row/column for data, fixed row/column for custom content
+ - support tsv/csv pasting (depends on Papaparse)
 
 
 ## Usage