Add install instruction to README.md

Closes #315
Closes #363

Signed-off-by: rusty-snake <41237666+rusty-snake@users.noreply.github.com>

Author: rusty-snake

README.md

@@ -62,6 +62,30 @@ clusters.  Having the ability for unprivileged users to use container
 features would make it significantly easier to do interactive
 debugging scenarios and the like.
 
+Installation
+------------
+
+bubblewrap is available in the package repositories of the most Linux distributions
+and can be installed from there.
+
+If you need to build bubblewrap from source, you can do this with meson or autotools.
+
+meson:
+
+```
+meson _builddir
+meson compile -C _builddir
+meson install -C _builddir
+```
+
+autotools:
+
+```
+./autogen.sh
+make
+sudo make install
+```
+
 Usage
 -----