qeury: add README.md with few examples

query/README.md

@@ -0,0 +1,71 @@
+# xash3d-query
+
+Receive and display information about servers.
+
+# Usage
+
+Fetch information about a server.
+
+```sh
+$ xash3d-query info 144.49.47.88:27016
+server: 144.49.47.88:27016 [33.462 ms]
+    status: "ok"
+    host: "Test Server"
+    gamedir: "valve"
+    map: "crossfire"
+    protocol: "0"
+    numcl: "13"
+    maxcl: "30"
+    dm: "true"
+    team: "false"
+    coop: "false"
+    password: "false"
+```
+
+Fetch servers addresses from the master server.
+
+```sh
+$ xash3d-query list
+144.49.47.88:27016
+144.49.47.88:27017
+```
+
+Fetch information about all servers received from the master server.
+
+```sh
+$ xash3d-query
+server: 144.49.47.88:27016 [33.462 ms]
+    status: "ok"
+    host: "Test Server"
+    gamedir: "valve"
+    map: "crossfire"
+    protocol: "0"
+    numcl: "13"
+    maxcl: "30"
+    dm: "true"
+    team: "false"
+    coop: "false"
+    password: "false"
+
+server: 144.49.47.88:27017 [32.596 ms]
+    status: "ok"
+    host: "Test Server 2"
+    gamedir: "valve"
+    map: "crossfire"
+    protocol: "0"
+    numcl: "7"
+    maxcl: "30"
+    dm: "true"
+    team: "false"
+    coop: "false"
+    password: "false"
+```
+
+# JSON output
+
+```sh
+# Print table sorted by number of players.
+$ xash3d-query -j | jq -r '[.servers[] | select(.status == "ok")] | sort_by(.numcl) | reverse | .[] | [.numcl, .map, .address, .host] | @tsv'
+13      crossfile       144.49.47.88:27016    Test Server
+7       crossfile       144.49.47.88:27017    Test Server 2
+```