Remove derp.yaml, add selfhosted example

This PR will promote fetching the derpmap directly from tailscale, so we
will remove our example, as it might easily get outdated.

Add a derp-example that shows how a user can also add their own derp
server.

derp-example.yaml

@@ -0,0 +1,18 @@
+# This file contains some of the official Tailscale DERP servers, 
+# shamelessly taken from https://github.com/tailscale/tailscale/blob/main/net/dnsfallback/dns-fallback-servers.json
+#
+# If you plan to somehow use headscale, please deploy your own DERP infra: https://tailscale.com/kb/1118/custom-derp-servers/
+regions: 
+  900:
+    regionid: 900
+    regioncode: custom
+    regionname: My Region
+    nodes:
+    - name: 1a
+      regionid: 1
+      hostname: myderp.mydomain.no
+      ipv4: 123.123.123.123
+      ipv6: "2604:a880:400:d1::828:b001"
+      stunport: 0
+      stunonly: false
+      derptestport: 0

derp.yaml

@@ -1,146 +0,0 @@
-# This file contains some of the official Tailscale DERP servers, 
-# shamelessly taken from https://github.com/tailscale/tailscale/blob/main/net/dnsfallback/dns-fallback-servers.json
-#
-# If you plan to somehow use headscale, please deploy your own DERP infra: https://tailscale.com/kb/1118/custom-derp-servers/
-regions: 
-  1:
-    regionid: 1
-    regioncode: nyc
-    regionname: New York City
-    nodes:
-    - name: 1a
-      regionid: 1
-      hostname: derp1.tailscale.com
-      ipv4: 159.89.225.99
-      ipv6: "2604:a880:400:d1::828:b001"
-      stunport: 0
-      stunonly: false
-      derptestport: 0
-    - name: 1b
-      regionid: 1
-      hostname: derp1b.tailscale.com
-      ipv4: 45.55.35.93
-      ipv6: "2604:a880:800:a1::f:2001"
-      stunport: 0
-      stunonly: false
-      derptestport: 0
-  2:
-    regionid: 2
-    regioncode: sfo
-    regionname: San Francisco
-    nodes:
-    - name: 2a
-      regionid: 2
-      hostname: derp2.tailscale.com
-      ipv4: 167.172.206.31
-      ipv6: "2604:a880:2:d1::c5:7001"
-      stunport: 0
-      stunonly: false
-      derptestport: 0
-    - name: 2b
-      regionid: 2
-      hostname: derp2b.tailscale.com
-      ipv4: 64.227.106.23
-      ipv6: "2604:a880:4:1d0::29:9000"
-      stunport: 0
-      stunonly: false
-      derptestport: 0
-  3:
-    regionid: 3
-    regioncode: sin
-    regionname: Singapore
-    nodes:
-    - name: 3a
-      regionid: 3
-      hostname: derp3.tailscale.com
-      ipv4: 68.183.179.66
-      ipv6: "2400:6180:0:d1::67d:8001"
-      stunport: 0
-      stunonly: false
-      derptestport: 0
-  4:
-    regionid: 4
-    regioncode: fra
-    regionname: Frankfurt
-    nodes:
-    - name: 4a
-      regionid: 4
-      hostname: derp4.tailscale.com
-      ipv4: 167.172.182.26
-      ipv6: "2a03:b0c0:3:e0::36e:900"
-      stunport: 0
-      stunonly: false
-      derptestport: 0
-    - name: 4b
-      regionid: 4
-      hostname: derp4b.tailscale.com
-      ipv4: 157.230.25.0
-      ipv6: "2a03:b0c0:3:e0::58f:3001"
-      stunport: 0
-      stunonly: false
-      derptestport: 0
-  5:
-    regionid: 5
-    regioncode: syd
-    regionname: Sydney
-    nodes:
-    - name: 5a
-      regionid: 5
-      hostname: derp5.tailscale.com
-      ipv4: 103.43.75.49
-      ipv6: "2001:19f0:5801:10b7:5400:2ff:feaa:284c"
-      stunport: 0
-      stunonly: false
-      derptestport: 0
-  6:
-    regionid: 6
-    regioncode: blr
-    regionname: Bangalore
-    nodes:
-    - name: 6a
-      regionid: 6
-      hostname: derp6.tailscale.com
-      ipv4: 68.183.90.120
-      ipv6: "2400:6180:100:d0::982:d001"
-      stunport: 0
-      stunonly: false
-      derptestport: 0
-  7:
-    regionid: 7
-    regioncode: tok
-    regionname: Tokyo
-    nodes:
-    - name: 7a
-      regionid: 7
-      hostname: derp7.tailscale.com
-      ipv4: 167.179.89.145
-      ipv6: "2401:c080:1000:467f:5400:2ff:feee:22aa"
-      stunport: 0
-      stunonly: false
-      derptestport: 0
-  8:
-    regionid: 8
-    regioncode: lhr
-    regionname: London
-    nodes:
-    - name: 8a
-      regionid: 8
-      hostname: derp8.tailscale.com
-      ipv4: 167.71.139.179
-      ipv6: "2a03:b0c0:1:e0::3cc:e001"
-      stunport: 0
-      stunonly: false
-      derptestport: 0
-  9:
-    regionid: 9
-    regioncode: sao
-    regionname: São Paulo
-    nodes:
-    - name: 9a
-      regionid: 9
-      hostname: derp9.tailscale.com
-      ipv4: 207.148.3.137
-      ipv6: "2001:19f0:6401:1d9c:5400:2ff:feef:bb82"
-      stunport: 0
-      stunonly: false
-      derptestport: 0