fix readme

Author: tpmanc

README.md

@@ -19,7 +19,7 @@ to the require section of your `composer.json` file.
 
 ## File reading
 
-`file.csv`:
+file.csv:
 ```
 Russia;Moscow;
 France;Paris;
@@ -45,7 +45,7 @@ Great Gritain: London
 
 ## Custom delimiter
 
-`file.csv`:
+file.csv:
 ```
 Russia|Moscow|
 France|Paris|
@@ -71,7 +71,7 @@ Great Gritain: London
 
 ## Offset and limit
 
-`file.csv`:
+file.csv:
 ```
 Russia;Moscow;
 France;Paris;
@@ -95,7 +95,7 @@ France: Paris
 
 ## Using variables from the parent scope
 
-`file.csv`:
+file.csv:
 ```
 Russia;Moscow;
 France;Paris;