alsa: document default profile set a bit better

src/modules/alsa/mixer/profile-sets/default.conf

@@ -1,22 +1,43 @@
-# Profile definitions for PulseAudio's ALSA backend
+# This file is part of PulseAudio.
 #
-# [Mapping id]
-# device-strings = ...
-# channel-map = ...
-# description = ...
-# paths-input = ...
-# paths-output = ...
-# element-input = ...
-# element-output = ...
-# priority = ...
-# direction = any | input | output
+# PulseAudio is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as
+# published by the Free Software Foundation; either version 2.1 of the
+# License, or (at your option) any later version.
 #
-# [Profile id]
-# input-mappings = ...
-# output-mappings = ...
-# description = ...
-# priority = ...
-# skip-probe = no | yes
+# PulseAudio is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with PulseAudio; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+
+; Default profile definitions for the ALSA backend of PulseAudio. This
+; is used as fallback for all cards that have no special mapping
+; assigned. (and should be good enough for the vast majority of cards)
+;
+; [General]
+; auto-profiles = no | yes                  # Instead of defining all profiles manually, autogenerate them by combining every input mapping with every output mapping.
+;
+; [Mapping id]
+; device-strings = ...                      # ALSA device string. %f will be replaced by the card identifier.
+; channel-map = ...                         # Channel mapping to use for this device
+; description = ...
+; paths-input = ...                         # A list of mixer paths to use. Every path in this list will be probed. If multiple are found to be working they will be available as device ports
+; paths-output = ...
+; element-input = ...                       # Instead of configuring a full mixer path simply configure a single mixer element for volume/mute handling
+; element-output = ...
+; priority = ...
+; direction = any | input | output          # Only useful for?
+;
+; [Profile id]
+; input-mappings = ...                      # Lists mappings for sources on this profile, those mapping must be defined in this file too
+; output-mappings = ...                     # Lists mappings for sinks on this profile, those mappings must be defined in this file too
+; description = ...
+; priority = ...                            # Numeric value to deduce priority for this profile
+; skip-probe = no | yes                     # Skip probing for availability?
 
 [General]
 auto-profiles = yes
@@ -99,6 +120,7 @@ channel-map = left,right
 priority = 4
 direction = output
 
+; An example for defining multiple-sink profiles
 #[Profile output:analog-stereo+output:iec958-stereo+input:analog-stereo]
 #description = Foobar
 #output-mappings = analog-stereo iec958-stereo