docs: update to show preferred boolean syntax for -chardev

The preferred syntax is to use "foo=on|off", rather than a bare
"foo" or "nofoo".

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210216191027.595031-8-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

docs/system/cpu-hotplug.rst

@@ -14,7 +14,7 @@ vCPU hotplug
       $ qemu-system-x86_64 -display none -no-user-config -m 2048 \
           -nodefaults -monitor stdio -machine pc,accel=kvm,usb=off \
           -smp 1,maxcpus=2 -cpu IvyBridge-IBRS \
-          -qmp unix:/tmp/qmp-sock,server,nowait
+          -qmp unix:/tmp/qmp-sock,server=on,wait=off
 
 (2) Run 'qmp-shell' (located in the source tree, under: "scripts/qmp/)
     to connect to the just-launched QEMU::

docs/system/s390x/3270.rst

@@ -24,7 +24,7 @@ Example configuration
 
 * Add a ``tn3270`` chardev and a ``x-terminal3270`` to the QEMU command line::
 
-   -chardev socket,id=ch0,host=0.0.0.0,port=2300,nowait,server,tn3270
+   -chardev socket,id=ch0,host=0.0.0.0,port=2300,wait=off,server=on,tn3270=on
    -device x-terminal3270,chardev=ch0,devno=fe.0.000a,id=terminal0
 
 * Start the guest. In the guest, use ``chccwdev -e 0.0.000a`` to enable

docs/system/target-avr.rst

@@ -24,7 +24,7 @@ AVR cpu
 - Continuous non interrupted execution with serial output into telnet window::
 
    qemu-system-avr -M mega2560 -bios demo.elf -nographic \
-                   -serial tcp::5678,server,nowait
+                   -serial tcp::5678,server=on,wait=off
 
   and then in another shell::