Fix some release note formatting

Fix the current notes that used single-backticks where
double-backticks should have been used.

Change-Id: I454e14dd084c9b706fab3255170a79765091a497

releasenotes/notes/bug-1520003-505af921c8afffc9.yaml

@@ -1,5 +1,5 @@
 ---
 fixes:
   - |
-    Add remote security group to `os security group rule list`
+    Add remote security group to ``os security group rule list``
     [Bug `1520003 <https://bugs.launchpad.net/bugs/1520003>`_]

releasenotes/notes/bug-1527833-42cde11d28b09ac3.yaml

@@ -1,7 +1,7 @@
 ---
 other:
-  - Change the `--owner` option to `--project` in `image create`
-    and `image set` commands.  `--owner` is deprecated and no longer
+  - Change the ``--owner`` option to ``--project`` in ``image create``
+    and ``image set`` commands.  ``--owner`` is deprecated and no longer
     documented but is still accepted; a warning message will be shown
     if it is used.
     [Bug `1527833 <https://bugs.launchpad.net/bugs/1527833>`_]

releasenotes/notes/bug-1532945-1a5485b8d0ebddb8.yaml

@@ -1,8 +1,8 @@
 ---
 features:
   - |
-    Add volume support to `os availability zone list`
+    Add volume support to ``os availability zone list``
     [Bug `1532945 <https://bugs.launchpad.net/bugs/1532945>`_]
 
-    * New `--compute` option to only list compute availability zones.
-    * New `--volume` option to only list volume availability zones.
+    * New ``--compute`` option to only list compute availability zones.
+    * New ``--volume`` option to only list volume availability zones.

releasenotes/notes/bug-1534202-1ba78f0bb744961f.yaml

@@ -1,7 +1,7 @@
 ---
 features:
   - |
-    Add network support to `os availability zone list`
+    Add network support to ``os availability zone list``
     [Bug `1534202 <https://bugs.launchpad.net/bugs/1534202>`_]
 
-    * New `--network` option to only list network availability zones.
+    * New ``--network`` option to only list network availability zones.