Updated the docs to reflect the changes from #18.

Author: StuntsPT

README.md

@@ -37,7 +37,7 @@ The program takes a few arguments:
 * Minimum K (optional - use as a start value for "K" - by default the value is 1; --min_K)
 * No-tests (optional - use this if you do not want to run the BestK tests; --no-tests)
 * No-plots (optional - use this if you do not want to draw plots; --no-plots)
-* Popfile (optional - use this if you want to name your populations in the plot. Should be a text file with 2 columns, one for the population name, and another for number of individuals represented in that population.)
+* Popfile (optional - use this if you want to name your populations in the plot. Should be a text file with 3 columns, one for population name, one for number of individuals represented in that population and one for the population position in the input file. This effectively allows the plot to be drawn in any chosen order.)
 
 Example: