Rename to README.md, update to current status

README.md

@@ -1,5 +1,16 @@
-Partials modification formula fatures
+# `soundeditor`
-=====================================
+
+This project is a Qt4/5 port of ATSH, a Gtk 1.2 GUI to the ATS system.
+
+## Dependencies
+
+- CMake `>= 3.13.5`.
+- [`libsndfile`](http://www.mega-nerd.com/libsndfile/) (`libsndfile1-dev`
+package on Debian/Ubuntu).
+
+##
+
+## Partials modification formula fatures
 
 Predefined variables :
 - P = number of partials
@@ -23,3 +34,9 @@ Examples:
      f = f*F(pr,tr)/F(pr,t)
 
   Ex: xj220b.ats : f = f*F(38,42)/F(38,t)
+
+## License
+
+See [`COPYING.txt`](COPYING.txt). Third-party libraries with various free
+licenses are also used - see [`COPYRIGHT.txt`](COPYRIGHT.txt) for further
+reference.