docs/tools/qemu-trace-stap.rst: Do not hard-code the QEMU binary name

In downstream, we want to use a different name for the QEMU binary,
and some people might also use the docs for non-x86 binaries, that's
why we already created the |qemu_system| placeholder in the past.
Use it now in the stap trace doc, too.

Message-Id: <20220104103319.179870-1-thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

docs/tools/qemu-trace-stap.rst

@@ -46,19 +46,19 @@ The following commands are valid:
   any of the listed names. If no *PATTERN* is given, the all possible
   probes will be listed.
 
-  For example, to list all probes available in the ``qemu-system-x86_64``
+  For example, to list all probes available in the |qemu_system|
   binary:
 
-  ::
+  .. parsed-literal::
 
-    $ qemu-trace-stap list qemu-system-x86_64
+    $ qemu-trace-stap list |qemu_system|
 
   To filter the list to only cover probes related to QEMU's cryptographic
   subsystem, in a binary outside ``$PATH``
 
-  ::
+  .. parsed-literal::
 
-    $ qemu-trace-stap list /opt/qemu/4.0.0/bin/qemu-system-x86_64 'qcrypto*'
+    $ qemu-trace-stap list /opt/qemu/|version|/bin/|qemu_system| 'qcrypto*'
 
 .. option:: run OPTIONS BINARY PATTERN...
 
@@ -90,26 +90,26 @@ The following commands are valid:
     Restrict the tracing session so that it only triggers for the process
     identified by *PID*.
 
-  For example, to monitor all processes executing ``qemu-system-x86_64``
+  For example, to monitor all processes executing |qemu_system|
   as found on ``$PATH``, displaying all I/O related probes:
 
-  ::
+  .. parsed-literal::
 
-    $ qemu-trace-stap run qemu-system-x86_64 'qio*'
+    $ qemu-trace-stap run |qemu_system| 'qio*'
 
   To monitor only the QEMU process with PID 1732
 
-  ::
+  .. parsed-literal::
 
-    $ qemu-trace-stap run --pid=1732 qemu-system-x86_64 'qio*'
+    $ qemu-trace-stap run --pid=1732 |qemu_system| 'qio*'
 
   To monitor QEMU processes running an alternative binary outside of
   ``$PATH``, displaying verbose information about setup of the
   tracing environment:
 
-  ::
+  .. parsed-literal::
 
-    $ qemu-trace-stap -v run /opt/qemu/4.0.0/qemu-system-x86_64 'qio*'
+    $ qemu-trace-stap -v run /opt/qemu/|version|/bin/|qemu_system| 'qio*'
 
 See also
 --------