[amtk] docs: readme: update, simplify

[Sébastien Wilmet <swilmet src gnome org>]

commit 5840afdf82a03d1d59c0b35ab8bec12c5ab959ad
Author: Sébastien Wilmet <swilmet informatique-libre be>
Date:   Fri Apr 15 11:48:55 2022 +0200

    docs: readme: update, simplify

 README.md | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)
---
diff --git a/README.md b/README.md
index 1e30e0f..3f70c04 100644
--- a/README.md
+++ b/README.md
@@ -10,19 +10,11 @@ traditional UI or a modern UI with a GtkHeaderBar.
 The Amtk library is free software and is released under the terms of the GNU
 Lesser General Public License, see the `COPYING` file for more information.
 
-See also the [Amtk web page](https://wiki.gnome.org/Projects/Amtk).
-
 Dependencies
 ------------
 
-- GLib >= 2.56
-- GTK >= 3.22
-
-Installation
-------------
-
-To build the latest version of Amtk plus its dependencies from Git,
-[Jhbuild](https://wiki.gnome.org/Projects/Jhbuild) is recommended.
+- GLib
+- GTK 3
 
 Documentation
 -------------
@@ -30,7 +22,7 @@ Documentation
 See the `gtk_doc` Meson option. A convenient way to read the API documentation
 is with the [Devhelp](https://wiki.gnome.org/Apps/Devhelp) application.
 
-How to contribute
------------------
+Development and maintenance
+---------------------------
 
-See the file `HACKING`.
+The project is in low-maintenance state.