Update readme

README.md

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-# harbour-picross
-Picross game for SailfishOS
+# Picross for Sailfish OS
+## Idea of Picross puzzles
+Solve the puzzles to find the hidden pictures in the grid based on numeric clues. For every clue, there is a block of adjacent cells of that size in that row or column. The only unknown is the amount of empty space between the blocks - maybe before the first and after the last block, too - and that is the logic behind Picross.
+
+Levels are sorted by difficulty, and you have to complete one difficulty to unlock the next one. At the moment, there are 103 levels spread across six difficulties.
+
+## About this fork
+The original [harbour-picross](https://github.com/Baspar/harbour-picross) was developed by @Baspar, along with most of the current levels.  As the last version released didn't work anymore (without applying [https://github.com/Baspar/harbour-picross/pull/4/commits/805254ddab46750d1f5b15ed5a046cbcaf899478](a patch)), I decided to fork it, fix it, tweak it and release it.
+
+## How to transfer Picross progress?
+### Background
+Because Jolla Store, naturally, does not allow two applications have a same name, I had to use a different name. Hence, Sailfish OS stores the data in different directory. Luckily this is the only thing that needs to be done: rename `harbour-picross` data storage folder structure to match `harbour-picross2`. That is, rename
+```
+~/.local/share/harbour-picross/harbour-picross/
+```
+to
+```
+~/.local/share/harbour-picross2/harbour-picross2/
+```
+Note that `harbour-picross` is listed twice in the path, and both directories must be renamed.
+
+### Step-by-step
+At the moment, this has to be done in terminal. Enable Developer mode in Settings, wait for the installation to succeed, and start the terminal.
+
+Please be careful whenever you use command line! Wrongly entered commands may lead to data loss! Ask for help if you are not confident!
+
+First, let's enter the application user data directory:
+```
+[nemo@jolla ~]$ cd .local/share/
+[nemo@jolla share]
+```
+If you have opened Picross 2, you have to move the new data out of the way:
+```
+[nemo@jolla share]$ mv harbour-picross2 harbour-picross2.bak
+```
+Now we can move the data from Picross to Picross 2! Due to the way Sailfish OS stores application data, this requires total of three commands:
+```
+[nemo@jolla share]$ mv harbour-picross harbour-picross2
+[nemo@jolla share]$ cd harbour-picross2
+[nemo@jolla harbour-picross2]$ mv harbour-picross harbour-picross2
+```
+If someone finds out a way to rename folders in QML-only Sailfish application, please let me know.
+
+# Great! How can I help?
+If you find bugs, want to translate the strings or submit new levels, you can make a pull request! Or, if that seems too tedious, you can just create a new issue and post it there.
+
+Happy solving!