Updated Format specification (markdown)

Format-specification.md

@@ -55,7 +55,7 @@ Sometimes you will not get nice progress during conversion, nonetheless you will
 
 # Progress function format
 
-Progress function are simple [Lua](http://www.lua.org/manual/5.3/) scripts with defined `GetProgress` function. The `progress` file extension is used instead of `lua`.
+Progress function are simple [Lua](http://www.lua.org/manual/5.3/) scripts with defined `GetProgress` function. The `lua` file extension is used.
 
 The progress function signature:
 
@@ -65,7 +65,7 @@ function GetProgress(s)
 
 Most of the Lua progress scripts are using [string manipulation](http://www.lua.org/manual/5.3/manual.html#6.4) with [patterns](http://lua-users.org/wiki/PatternsTutorial).
 
-For a quick start use one of the [existing](https://github.com/wieslawsoltes/BatchEncoder/tree/master/config/progress) progress scripts.
+For a quick start use one of the [existing](https://github.com/wieslawsoltes/BatchEncoder/tree/master/config/progress) Lua progress scripts.
 
 # Default progress functions