ASoC: doc: ReSTize dapm.txt

A simple conversion from a plain text file.
The section numbers and the item numbers are dropped to align with the
ReST format.  Some lists are converted to description lists to be
clearer.
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Documentation/sound/soc/index.rst

@@ -10,3 +10,4 @@ The documentation is spilt into the following sections:-
    overview
    codec
    dai
+   dapm