Add under the hood paragraph to README.md

Author: introfog

README.md

@@ -33,6 +33,11 @@ Explore, contribute, and customize the application according to your preferences
 - To run application execute `mvn javafx:run`.
 - To create ready to use app, archived into .zip, run `mvn package`. GitWave will be in `target/GitWave.zip` archive.
   - `GitWave.exe`, which run java image, is located in `tools` folder and generated by separate C++ project `tools/GitWaveExecutor`.
+ 
+## :gear: Under the hood
+- GitWave is built on openjdk 11 + openjfx 11.
+- All commands and settings are stored in `config/config.json` in JSON format. So it is possible to edit them manually in any text editor.
+- On openning app makes lenient request to GitHub API to check for the new available release, see `com.github.introfog.gitwave.model.UpdateChecker#isNewReleaseAvailable`.
 
 ## :bulb: Ideas For Further Releases
 - Allow working with app by using only keyboard (with correct Tabs, Esc and so on work).