mpv.conf: add some more options

Seems like questions related to functionality covered by them are quite
often asked.

etc/mpv.conf

@@ -38,6 +38,14 @@
 # don't allow a new window to have a size larger than 90% of the screen size
 #autofit-larger=90%x90%
 
+# Do not close the window on exit.
+#keep-open=yes
+
+# Do not wait with showing the video window until it has loaded. (This will
+# resize the window once video is loaded. Also always shows a window with
+# audio.)
+#force-window=immediate
+
 # Disable the On Screen Controller (OSC).
 #osc=no