docs: perf: Add imx-ddr to documentation index

Sphinx is currently outputting a warning where
the file 'imx-ddr.rst' is not included in the
documentation index. Additionally, the code
highlighting and doc formatting can be slightly
improved.

Signed-off-by: Adam Zerella <[e-mail]>
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/admin-guide/perf/imx-ddr.rst

···
 devices/imx8_ddr0/format/. The "events" directory describes the events types
 hardware supported that can be used with perf tool, see /sys/bus/event_source/
 devices/imx8_ddr0/events/.
-  e.g.::
+
+    .. code-block:: bash
+
         perf stat -a -e imx8_ddr0/cycles/ cmd
         perf stat -a -e imx8_ddr0/read/,imx8_ddr0/write/ cmd
 
···
   Filter is defined with two configuration parts:
   --AXI_ID defines AxID matching value.
   --AXI_MASKING defines which bits of AxID are meaningful for the matching.
-        0：corresponding bit is masked.
-        1: corresponding bit is not masked, i.e. used to do the matching.
+
+      - 0: corresponding bit is masked.
+      - 1: corresponding bit is not masked, i.e. used to do the matching.
 
   AXI_ID and AXI_MASKING are mapped on DPCR1 register in performance counter.
   When non-masked bits are matching corresponding AXI_ID bits then counter is
   incremented. Perf counter is incremented if
-          AxID && AXI_MASKING == AXI_ID && AXI_MASKING
+        AxID && AXI_MASKING == AXI_ID && AXI_MASKING
 
   This filter doesn't support filter different AXI ID for axid-read and axid-write
   event at the same time as this filter is shared between counters.
-  e.g.::
-        perf stat -a -e imx8_ddr0/axid-read,axi_mask=0xMMMM,axi_id=0xDDDD/ cmd
-        perf stat -a -e imx8_ddr0/axid-write,axi_mask=0xMMMM,axi_id=0xDDDD/ cmd
 
-  NOTE: axi_mask is inverted in userspace(i.e. set bits are bits to mask), and
-  it will be reverted in driver automatically. so that the user can just specify
-  axi_id to monitor a specific id, rather than having to specify axi_mask.
-  e.g.::
-        perf stat -a -e imx8_ddr0/axid-read,axi_id=0x12/ cmd, which will monitor ARID=0x12
+  .. code-block:: bash
+
+      perf stat -a -e imx8_ddr0/axid-read,axi_mask=0xMMMM,axi_id=0xDDDD/ cmd
+      perf stat -a -e imx8_ddr0/axid-write,axi_mask=0xMMMM,axi_id=0xDDDD/ cmd
+
+  .. note::
+
+      axi_mask is inverted in userspace(i.e. set bits are bits to mask), and
+      it will be reverted in driver automatically. so that the user can just specify
+      axi_id to monitor a specific id, rather than having to specify axi_mask.
+
+  .. code-block:: bash
+
+      perf stat -a -e imx8_ddr0/axid-read,axi_id=0x12/ cmd, which will monitor ARID=0x12

Documentation/admin-guide/perf/index.rst

···
    :maxdepth: 1
 
    hisi-pmu
+   imx-ddr
    qcom_l2_pmu
    qcom_l3_pmu
    arm-ccn