Update README

Author: Tearth

README.md

@@ -1,6 +1,8 @@
 # PGN2ABK
 This is the simple tool to generate ABK (Arena's book format) files using a collection of games saved in the PGN file. There are several sources of PGN files, my favorite one is https://database.lichess.org/. It takes about 30 minutes to parse 190 GB file on normal HDD.
 
+Program has been written in C# for .NET Core 3 platform. It uses [CommandLineParser](https://github.com/commandlineparser/commandline) (to parse parameters) and [ShellProgressBar](https://github.com/Mpdreamz/shellprogressbar).
+
 # Usage
 
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