Fix formatting for virDomainGetCPUStats docstring

We have few code samples there that are almost unreadable when formatted
because they are not indented properly.  By indenting them they are
formatted as code and hence quite readable.  Also adjust descriptions to
be comments and add semicolons so that the code sample looks like sample
of a working code.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

src/libvirt-domain.c

@@ -10572,15 +10572,17 @@ virDomainGetBlockIoTune(virDomainPtr dom,
  * Typical use sequence is below.
  *
  * getting total stats: set start_cpu as -1, ncpus 1
- * virDomainGetCPUStats(dom, NULL, 0, -1, 1, 0) => nparams
- * params = calloc(nparams, sizeof(virTypedParameter))
- * virDomainGetCPUStats(dom, params, nparams, -1, 1, 0) => total stats.
+ *
+ *   virDomainGetCPUStats(dom, NULL, 0, -1, 1, 0); // nparams
+ *   params = calloc(nparams, sizeof(virTypedParameter))
+ *   virDomainGetCPUStats(dom, params, nparams, -1, 1, 0); // total stats.
  *
  * getting per-cpu stats:
- * virDomainGetCPUStats(dom, NULL, 0, 0, 0, 0) => ncpus
- * virDomainGetCPUStats(dom, NULL, 0, 0, 1, 0) => nparams
- * params = calloc(ncpus * nparams, sizeof(virTypedParameter))
- * virDomainGetCPUStats(dom, params, nparams, 0, ncpus, 0) => per-cpu stats
+ *
+ *   virDomainGetCPUStats(dom, NULL, 0, 0, 0, 0); // ncpus
+ *   virDomainGetCPUStats(dom, NULL, 0, 0, 1, 0); // nparams
+ *   params = calloc(ncpus * nparams, sizeof(virTypedParameter));
+ *   virDomainGetCPUStats(dom, params, nparams, 0, ncpus, 0); // per-cpu stats
  *
  * Returns -1 on failure, or the number of statistics that were
  * populated per cpu on success (this will be less than the total