Make README.rst more friendly for beginner (#48)

As a beginner of jsoncsv, I found README.rst can be more clearly and beautiful for beginner. This commit can make README.rst more beautiful and friendly. Btw,  GitHub is not support .rst file every well. Could you consider change README to .md file?

Author: thtTNT

README.rst

@@ -2,12 +2,14 @@
 jsoncsv : easily convert json to csv or xls[x]
 ==============================================
 
-.. image:: https://img.shields.io/pypi/v/jsoncsv.svg
+ |pypi|  |build|  |coverage|
+
+.. |pypi| image:: https://img.shields.io/pypi/v/jsoncsv.svg
     :target: https://pypi.python.org/pypi/jsoncsv
 
-.. image:: https://api.travis-ci.org/alingse/jsoncsv.svg?branch=master
+.. |build| image:: https://api.travis-ci.org/alingse/jsoncsv.svg?branch=master
 
-.. image:: https://coveralls.io/repos/github/alingse/jsoncsv/badge.svg
+.. |coverage| image:: https://coveralls.io/repos/github/alingse/jsoncsv/badge.svg
     :target: https://coveralls.io/github/alingse/jsoncsv
 
 
@@ -20,41 +22,58 @@ Just use them.
 Quick Start :
 =================
 
-cat the raw.json to csv/xls use command line tool
+Cat the raw.json to csv/xls use command line tool
 
 .. code-block:: bash
 
     cat raw.json | jsoncsv | mkexcel > output.csv
     cat raw.json | jsoncsv | mkexcel -t xls > output.xls
 
-make sure each line of raw json text file is a json object
+Each line of raw json text file is a json object
 
-.. code-block:: bash
+.. code-block:: json
 
-    $cat raw.json
     {"id":1, "name":"A", "year": 2015}
     {"id":2, "name":"S", "zone": "china"}
-    $cat raw.json | jsoncsv | mkexcel > output.csv
-    $cat output.csv
+
+Jsoncsv will output a csv file
+
+.. code-block:: 
+
     id,name,year,zone
     1,A,2015,
     2,S,,china
 
 This is easily and needn't care the different keys from any two object.
 
-if input file is an json_array, use `-A/--array` to decode it
+For Json Array
+-------------------
+
+If input file is an json_array, use `-A/--array` to decode it
 
 .. code-block:: bash
 
-    $cat raw.json
-    [{"id":1, "name":"A", "year": 2015}, {"id":2, "name":"S", "zone": "china"}]
-    $cat raw.json | jsoncsv -A | mkexcel > output.csv
-    $cat output.csv
+	cat raw.json | jsoncsv -A | mkexcel > output.csv	
+
+**Input File**
+
+.. code-block:: json
+
+	[
+	    {"id":1, "name":"A", "year": 2015}, 
+	    {"id":2, "name":"S", "zone": "china"}
+	]
+
+**Output File**
+
+.. code-block::
+
     id,name,year,zone
     1,A,2015,
     2,S,,china
 
-another way to convert file step by step
+Step by Step
+---------------------------
 
 .. code-block:: bash