Add instructions

README.md

+# Librem 5 Package Information Tool
+
+This application reads and displays information about the installed PureOS
+packages on the Librem 5 phone.
+
+## Building the Application
+
+The application can be configured using the Meson and Ninja build systems.
+To configure the build, run `meson` and specify the source and build
+directories:
+
+``` bash
+meson . _build
+```
+
+Build the application using `ninja`, passing the build directory as an
+argument so that the build occurs within that directory:
+
+``` bash
+ninja -C _build
+```
+
+The default rule is to build the application.
+
+Finally, install the application to a standard location:
+
+``` bash
+ninja -C _build install
+```
+
+Installing to a standard system location will generally require `sudo` to be
+used.
+
+## License
+
+The source code is licensed under the GNU General Public License version 3 or
+later. See the COPYING file for more information about this license. A summary
+of the copyright and license is given below:
+
+Copyright (C) 2019 Purism SPC
+SPDX-License-Identifier: GPL-3.0+
+Author: David Boddie <david.boddie@puri.sm>