Fixed typo

Author: dan-coulter

README.md

@@ -8,7 +8,7 @@ Installation
 ============
 
 1.  Copy the files from the installation package into a folder on your
-    server.  They need to be readible by your web server.  You can put 
+    server.  They need to be readable by your web server.  You can put 
     them into an include folder defined in your php.ini file, if you 
     like, though it's not required.