README.rst: Change README.md's image

This is to replace the image at coala-html repository
in README.md file with that of coala-bears.

Closes coala#151

README.rst

@@ -1,26 +1,6 @@
 README
 ======
-
-.. Start ignoring LineLengthBear
-
-::
-
-                                                         .o88Oo._
-                                                        d8P         .ooOO8bo._
-                                                        88                  '*Y8bo.
-                                          __            YA                      '*Y8b   __
-                                        ,dPYb,           YA                        68o68**8Oo.
-                                        IP'`Yb            "8D                       *"'    "Y8o
-                                        I8  8I             Y8     'YB                       .8D
-                                        I8  8P             '8               d8'             8D
-                                        I8  8'              8       d8888b          d      AY
-         ,gggo,    ,ggggo,    ,gggo,gg  I8 dP    ,gggo,gg   Y,     d888888         d'  _.oP"
-        dP"  "Yb  dP"  "Y8go*8P"  "Y8I  I8dP    dP"  "Y8I    q.    Y8888P'        d8
-       i8'       i8'    ,8P i8'    ,8I  I8P    i8'    ,8I     "q.  `Y88P'       d8"
-      ,d8,_    _,d8,   ,d8' d8,   ,d8b,,d8b,_ ,d8,   ,d8b,       Y           ,o8P
-    ooP""Y8888PP*"Y8888P"   "Y8888P"`Y88P'"Y88P"Y8888P"`Y8            oooo888P"
-
-.. Stop ignoring LineLengthBear
+.. image:: https://cloud.githubusercontent.com/assets/7521600/15992701/ef245fd4-30ef-11e6-992d-275c5ca7c3a0.jpg
 
 ABOUT
 =====