systemd/timesyncd.conf.d: sync sources from Chrony

This is for SteamOS, although without Yggdrasil (that I am not hacking in
yet) and NTS which systemd-timesyncd doesn't do to my knowledge

etc/systemd/timesyncd.conf.d/00-fallback-poolntporg.conf

@@ -0,0 +1,2 @@
+[Time]
+FallbackNTP=pool.ntp.org

etc/systemd/timesyncd.conf.d/README.md

@@ -0,0 +1,10 @@
+# systemd-timesyncd source configuration
+
+For more information about the time servers, refer to their websites or
+`../../chrony/sources.d` which comes with more detailed comments. Chrony
+is my preferred NTP client/server, but SteamOS happens to come with
+systemd-timesyncd enabled and using the pool.ntp.org, so I had to revive this
+at least partially.
+
+It looks like multiple files can be used simultaneously judging by
+`timedatectl show-timesync`

etc/systemd/timesyncd.conf.d/cloudflare.conf

@@ -1,3 +1,2 @@
 [Time]
 NTP=time.cloudflare.com
-FallbackNTP=pool.ntp.org

etc/systemd/timesyncd.conf.d/dna-moi.conf

@@ -0,0 +1,2 @@
+[Time]
+NTP=ntp.dnainternet.fi

etc/systemd/timesyncd.conf.d/elisa.conf

@@ -0,0 +1,2 @@
+[Time]
+NTP=ntp1.kolumbus.fi ntp2.kolumbus.fi ntp.saunalahti.fi

etc/systemd/timesyncd.conf.d/finland.conf

@@ -0,0 +1,2 @@
+[Time]
+NTP=time.mikes.fi time1.mikes.fi time2.mikes.fi time3.mikes.fi

etc/systemd/timesyncd.conf.d/hetzner.conf

@@ -0,0 +1,2 @@
+[Time]
+NTP=ntp.hetzner.de

etc/systemd/timesyncd.conf.d/telia.conf

@@ -0,0 +1,2 @@
+[Time]
+NTP=ntp.inet.fi