improve documentation

As per #1, the term 'columns' has been specified to refer to a unicode codepoint count

diagnose.cabal

@@ -5,8 +5,8 @@ cabal-version: 1.12
 -- see: https://github.com/sol/hpack
 
 name:           diagnose
-version:        1.6.3
-synopsis:       Beautiful error reporting done easily.
+version:        1.6.4
+synopsis:       Beautiful error reporting done easily
 description:    This package provides a simple way of getting beautiful compiler/interpreter errors
                 using a very simple interface for the programmer.
                 .

package.yaml

@@ -1,5 +1,5 @@
 name: diagnose
-version: 1.6.3
+version: 1.6.4
 github: "mesabloo/diagnose"
 license: BSD3
 author: "Ghilain Bergeron"
@@ -114,7 +114,7 @@ tests:
 
 
 # This is put at the end for convenience.
-synopsis: Beautiful error reporting done easily.
+synopsis: Beautiful error reporting done easily
  
 description: |
   This package provides a simple way of getting beautiful compiler/interpreter errors

src/Error/Diagnose/Position.hs

@@ -31,6 +31,9 @@ import Prettyprinter (Pretty (..), colon)
 --   > data Located a
 --   >   = a :@ Position
 --   >   deriving (Show, Eq, Ord, Functor, Traversable)
+--
+--   Columns are specified in amount of Unicode codepoints from the beginning of the line.
+--   Lines and columns start at 1.
 data Position = Position
   { -- | The beginning line and column of the span.
     begin :: (Int, Int),