example.conf: some modifications

Remove options which are too obscure and most likely not very useful in
general, or update them to something more modern. Add some comments
about how configuration files work in general.

etc/example.conf

@@ -3,23 +3,30 @@
 #
 # Configuration files are read system-wide from /usr/local/etc/mpv.conf
 # and per-user from ~/.mpv/config, where per-user settings override
-# system-wide settings, all of which are overrriden by the command line.
+# system-wide settings, all of which are overridden by the command line.
 #
-# The configuration file settings are the same as the command line
-# options without the preceding '--'.
+# Configuration file settings and the command line options use the same
+# underlying mechanisms. Most options can be put into the configuration file
+# by dropping the preceding '--'. See the man page for a complete list of
+# options.
+#
+# Lines starting with '#' are comments and are ignored.
 #
 # See the CONFIGURATION FILES section in the man page
 # for a detailed description of the syntax.
 #
 # Profiles should be placed at the bottom of the configuration file to ensure
 # that settings wanted as defaults are not restricted to specific profiles.
-
+#
+# Note that the commented example options usually do _not_ set the default
+# values. Calling mpv with --list-options is a nice way to see the default
+# values for most options.
 
 ##################
 # video settings #
 ##################
 
-# Specify default video driver (see -vo help for a list).
+# Specify default video driver (see --vo=help for a list).
 #vo=vdpau
 
 # Start in fullscreen mode by default.
@@ -39,7 +46,7 @@
 # audio settings #
 ##################
 
-# Specify default audio driver (see -ao help for a list).
+# Specify default audio driver (see --ao=help for a list).
 #ao=alsa
 
 # Disable softvol usage, and always use the system mixer if available.
@@ -50,20 +57,15 @@
 # other settings #
 ##################
 
-# Pretend to be Window Media Player.
-# Fixes playback when playlist and media file use the same URL.
-#user-agent=NSPlayer/4.1.0.3856
-
-# Pretend to be Winamp
-# Fixes playback of some NSV streams
-#user-agent="Winamp NSV Player/5.12 (ultravox/2.0)"
-
-# Drop frames to preserve audio/video sync.
-#framedrop = yes
+# Pretend to be a web browser. Might fix playback with some streaming sites.
+#user-agent="Mozilla/5.0"
 
 # cache settings
 #
-# Use 8MB input cache by default.
+# Use 8MB input cache by default. The cache is enabled for network streams only.
+#cache-default = 8192
+#
+# Use 8MB input cache for everything, even local files.
 #cache = 8192
 #
 # Prefill 20% of the cache before starting playback.
@@ -72,14 +74,11 @@
 # Prefill 50% of the cache before restarting playback after the cache emptied.
 #cache-seek-min = 50
 
-# DVD: Display English subtitles if available.
+# Display English subtitles if available.
 #slang = en
 
-# DVD: Play English audio tracks if available.
-#alang = en
-
-# Use this for a widescreen monitor, non-square pixels.
-#monitoraspect=16:9
+# Play Finnish audio if available, fall back to English otherwise.
+#alang = fi,en
 
 # Enable hardware decoding if available. Often, this requires using an certain
 # video output, otherwise no hardware decoding will be used.