docs/interop: Delete qmp-intro.txt

qmp-intro.txt is quite small and provides very little information
that isn't already in the documentation elsewhere.  Fold the example
command lines into qemu-options.hx, and delete the now-unneeded plain
text document.

While we're touching the qemu-options.hx documentation text,
wordsmith it a little bit and improve the rST formatting.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20230515162245.3964307-4-peter.maydell@linaro.org>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

docs/interop/qmp-intro.txt

@@ -1,88 +0,0 @@
-                          QEMU Machine Protocol
-                          =====================
-
-Introduction
-------------
-
-The QEMU Machine Protocol (QMP) allows applications to operate a
-QEMU instance.
-
-QMP is JSON[1] based and features the following:
-
-- Lightweight, text-based, easy to parse data format
-- Asynchronous messages support (ie. events)
-- Capabilities Negotiation
-
-For detailed information on QMP's usage, please, refer to the following files:
-
-o qmp-spec.txt      QEMU Machine Protocol current specification
-o qemu-qmp-ref.html QEMU QMP commands and events (auto-generated at build-time)
-
-[1] https://www.json.org
-
-Usage
------
-
-You can use the -qmp option to enable QMP. For example, the following
-makes QMP available on localhost port 4444:
-
-$ qemu [...] -qmp tcp:localhost:4444,server=on,wait=off
-
-However, for more flexibility and to make use of more options, the -mon
-command-line option should be used. For instance, the following example
-creates one HMP instance (human monitor) on stdio and one QMP instance
-on localhost port 4444:
-
-$ qemu [...] -chardev stdio,id=mon0 -mon chardev=mon0,mode=readline \
-             -chardev socket,id=mon1,host=localhost,port=4444,server=on,wait=off \
-             -mon chardev=mon1,mode=control,pretty=on
-
-Please, refer to QEMU's manpage for more information.
-
-Simple Testing
---------------
-
-To manually test QMP one can connect with telnet and issue commands by hand:
-
-$ telnet localhost 4444
-Trying 127.0.0.1...
-Connected to localhost.
-Escape character is '^]'.
-{
-    "QMP": {
-        "version": {
-            "qemu": {
-                "micro": 0,
-                "minor": 0,
-                "major": 3
-            },
-            "package": "v3.0.0"
-        },
-        "capabilities": [
-            "oob"
-        ]
-    }
-}
-
-{ "execute": "qmp_capabilities" }
-{
-    "return": {
-    }
-}
-
-{ "execute": "query-status" }
-{
-    "return": {
-        "status": "prelaunch", 
-        "singlestep": false, 
-        "running": false
-    }
-}
-
-Please refer to docs/interop/qemu-qmp-ref.* for a complete command
-reference, generated from qapi/qapi-schema.json.
-
-QMP wiki page
--------------
-
-https://wiki.qemu.org/QMP

qemu-options.hx

@@ -4170,26 +4170,42 @@ DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \
     QEMU_ARCH_ALL)
 SRST
 ``-qmp dev``
-    Like -monitor but opens in 'control' mode.
+    Like ``-monitor`` but opens in 'control' mode. For example, to make
+    QMP available on localhost port 4444::
+
+        -qmp tcp:localhost:4444,server=on,wait=off
+
+    Not all options are configurable via this syntax; for maximum
+    flexibility use the ``-mon`` option and an accompanying ``-chardev``.
+
 ERST
 DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \
     "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n",
     QEMU_ARCH_ALL)
 SRST
 ``-qmp-pretty dev``
-    Like -qmp but uses pretty JSON formatting.
+    Like ``-qmp`` but uses pretty JSON formatting.
 ERST
 
 DEF("mon", HAS_ARG, QEMU_OPTION_mon, \
     "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL)
 SRST
 ``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]``
-    Setup monitor on chardev name. ``mode=control`` configures 
+    Set up a monitor connected to the chardev ``name``.
-    a QMP monitor (a JSON RPC-style protocol) and it is not the
+    QEMU supports two monitors: the Human Monitor Protocol
-    same as HMP, the human monitor that has a "(qemu)" prompt.
+    (HMP; for human interaction), and the QEMU Monitor Protocol
+    (QMP; a JSON RPC-style protocol).
+    The default is HMP; ``mode=control`` selects QMP instead.
     ``pretty`` is only valid when ``mode=control``,
     turning on JSON pretty printing to ease
     human reading and debugging.
+
+    For example::
+
+      -chardev socket,id=mon1,host=localhost,port=4444,server=on,wait=off \
+      -mon chardev=mon1,mode=control,pretty=on
+
+    enables the QMP monitor on localhost port 4444 with pretty-printing.
 ERST
 
 DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \