update document

Author: jinhr9801

README.md

@@ -2,6 +2,71 @@
 
 This library implements:
 
-    A. Get file format from binary data, now support:
-        .jpeg
-        .png
+1. Get filename extension from file path
+2. Confirm filename extension by  file signature
+
+    Now support:
+    
+    PDF
+    ZIP
+    RAR
+    ISO
+    
+    JPEG
+    JPG
+    PNG
+    WEBP
+    GIF
+    TIFF
+    BMP
+    ICO
+    J2K
+    JP2
+    EPS
+    PSD
+    PSB
+    
+    M4A
+    M4B
+    M4P
+    M4V
+    MOV
+    
+    MP4
+    MP3
+    MP2
+    
+    WAV
+    AVI
+    AIFF
+    MID
+    FLAC
+    APE
+    RM
+    RMVB
+    
+    EXE
+
+    TXT
+    HTML
+    
+    DOC
+    DOCX
+    PPT
+    PPTX
+    XML
+    XMLX
+    
+    SVG
+    DIB
+    TGA
+    
+    WMA
+    WMV
+    ASF
+        
+    
+Reference:
+https://www.filesignatures.net/
+http://www.ftyps.com/
+http://www.nationalarchives.gov.uk/PRONOM/Format/proFormatSearch.aspx?status=new