etc/example.conf: update cache options

Some of them changed semantics or got renamed.

Note that the replacements in the example.conf are not necessarily the
equivalents of the replaced options.

etc/example.conf

@@ -80,11 +80,17 @@
 # Use 8MB input cache for everything, even local files.
 #cache=8192
 #
-# Prefill 20% of the cache before starting playback.
+# If a seek is issued, and the target is 1024KB past the cached range, then
-#cache-min=20.0
+# keep reading until the seek target is hit, instead of doing a real seek.
+#cache-seek-min=1024
 #
-# Prefill 50% of the cache before restarting playback after the cache emptied.
+# Disable the behavior that the player will pause if the cache goes below a
-#cache-seek-min=50
+# certain fill size.
+#cache-pause-below=no
+#
+# Enable demuxer-based cache. This reads ahead a number of packets, and the
+# player won't freeze completely if network is slow during playback.
+#demuxer-thread=yes
 
 # Display English subtitles if available.
 #slang=en