Tweak README.

README

@@ -6,6 +6,12 @@ You will need Go 1.13 or later (type `go version`).  Then do:
 
     CGO_ENABLED=0 go build -ldflags='-s -w'
 
+On Windows, do
+
+    set CGO_ENABLED=0
+    go build -ldflags='-s -w'
+
+
 ## Set the server administrator credentials
 
 This step is optional.
@@ -41,6 +47,7 @@ A group with one operator and two users looks like this:
     
 More options are described under *Details of group definitions* below.
 
+
 ## Test locally
 
     ./galene &
@@ -49,12 +56,6 @@ You should be able to access Galène at `https://localhost:8443`.  Connect
 to the group that you have just set up in two distinct browser windows,
 then press *Ready* in one of the two; you should see a video in the other.
 
-If you have set up a TURN server, type `/relay-test` in the chat box; if
-the TURN server is properly configured, you should see a message saying
-that the relay test has been successful.  (The relay test will fail if you
-didn't configure a TURN server; this is normal, and nothing to worry
-about.)
-
 ## Configure your server's firewall
 
 If your server has a global IPv4 address and there is no firewall, there
@@ -63,20 +64,19 @@ is nothing to do.
 If your server has a global IPv4 address, then the firewall must, at
 a strict minimum, allow incoming traffic to TCP port 8443 (or whatever is
 configured with the `-http` command-line option) and TCP port 1194 (or
-whatever is configured with the `-turn` command-line option).  For best
-performance, it should also allow UDP traffic to the TURN port, and UDP
-traffic to ephemeral (high-numbered) ports.
+whatever is configured with the `-turn` option).  For best performance, it
+should also allow UDP traffic to the TURN port, and UDP traffic to
+ephemeral (high-numbered) ports (or whatever is configured using the
+`-udp-range` option).
 
-If your server only has a global IPv6 address, then you should probably
-configure an external double-stack (IPv4 and IPv6) TURN server: see
-"ICE Servers" below.
+If your server is behind NAT, then the NAT must forward, at the very
+least, port 8443 to your server.  Ideally, you should configure an
+external TURN server (see *ICE Servers* below) on a host that is not
+behind NAT.  If that is not possible, then you should forward port 1194 in
+addition to port 8443, and you should add the option `-turn 203.0.113.1:1194`
+to Galène's command line, where `203.0.113.1` is your NAT's external
+(global) IPv4 address.
 
-If your server is behind NAT, then the best solution is to run an external
-TURN server that is not behind NAT (see "ICE Servers" below).  If that is
-not possible, then you should configure your NAT device to forward, at
-a minimum, ports 8443 (TCP) and 1194 (TCP and UDP).  In addition, you
-should add the option `-turn 203.0.113.1:1194` to Galène's command line,
-where `203.0.113.1` is your NAT's external (global) IPv4 address.
 
 ## Cross-compile for your server
 
@@ -103,6 +103,7 @@ For a 32-bit MIPS board with no hardware floating point (WNDR3800, etc.):
 
     CGO_ENABLED=0 GOOS=linux GOARCH=mips GOMIPS=softfloat go build -ldflags='-s -w'
 
+
 ## Deploy to your server
 
 Set up a user *galene* on your server, then do:
@@ -150,6 +151,7 @@ If you are using *systemd*:
     [Install]
     WantedBy=multi-user.target
 
+
 # Usage
 
 ## Locations
@@ -166,6 +168,7 @@ available to the administrator of the group.
 Some statistics are available under `/stats.json`, with a human-readable
 version at `/stats.html`.  This is only available to the server administrator.
 
+
 ## Side menu
 
 There is a menu on the right of the user interface.  This allows choosing
@@ -174,6 +177,7 @@ the camera and microphone and setting the video throughput.  The
 in favour of image quality.  The *Play local file* dialog allows streaming
 a video from a local file.
 
+
 ## Commands
 
 Typing a line starting with a slash `/` in the chat dialogue causes
@@ -273,6 +277,7 @@ user entry with a hashed password looks like this:
         }
     }
 
+
 # ICE Servers
 
 ICE is the NAT and firewall traversal protocol used by WebRTC.  ICE can
@@ -294,8 +299,8 @@ forwarding set up.  The default value is `-turn auto`, which starts a
 TURN server on port 1194 unless there is a `data/ice-servers.json` file.
 
 Some users may prefer to use an external ICE server.  In that case, the
-built-in TURN server should be disabled (`-turn ""` or the default `-turn
-auto`), and a working ICE configuration should be given in the file
+built-in TURN server should be disabled (`-turn ""` or the default
+`-turn auto`), and a working ICE configuration should be given in the file
 `data/ice-servers.json`.  In the case of a single STUN server, it should
 look like this:
 
@@ -341,10 +346,12 @@ first one that works.  If an `ice-servers.json` file is present and
 Galène's built-in TURN server is enabled, then the external server will be
 used in preference to the built-in server.
 
+
 # Further information
 
 Galène's web page is at <https://galene.org>.
 
 Answers to common questions and issues are at <https://galene.org#faq>.
 
+
 -- Juliusz Chroboczek <https://www.irif.fr/~jch/>