doc: make all manpages with Doxygen

Use (fixed-up) Doxygen manpage output for all program & module manpages.

This also allows formatting the manual pages properly in the HTML docs.

The Markdown pages work properly only with Doxygen >= 1.9.7, older
versions put them to wrong place in the HTML docs.

doc/dox/programs/pw-jack.1.md

@@ -0,0 +1,45 @@
+\page page_man_pw-jack_1 pw-jack
+
+Use PipeWire instead of JACK
+
+# SYNOPSIS
+
+**pw-jack** \[*options*\] *COMMAND* \[*FILE*\]
+
+# DESCRIPTION
+
+**pw-jack** modifies the `LD_LIBRARY_PATH` environment variable so that
+applications will load PipeWire's reimplementation of the JACK client
+libraries instead of JACK's own libraries. This results in JACK clients
+being redirected to PipeWire.
+
+If PipeWire's reimplementation of the JACK client libraries has been
+installed as a system-wide replacement for JACK's own libraries, then
+the whole system already behaves in that way, in which case **pw-jack**
+has no practical effect.
+
+# OPTIONS
+
+\par -h
+Show help.
+
+\par -r NAME
+The name of the remote instance to connect to. If left unspecified, a
+connection is made to the default PipeWire instance.
+
+\par -v
+Verbose operation.
+
+# EXAMPLES
+
+\par pw-jack sndfile-jackplay /usr/share/sounds/freedesktop/stereo/bell.oga
+
+# AUTHORS
+
+The PipeWire Developers <$(PACKAGE_BUGREPORT)>;
+PipeWire is available from <$(PACKAGE_URL)>
+
+# SEE ALSO
+
+\ref page_man_pipewire_1 "pipewire(1)",
+**jackd(1)**,