Fixup cl_khr_command_buffer after spec unification (#1089)

After PR #950 merged the cl_khr_command_buffer spec needs
updated in a couple of places:

* Error around _num_queues_ to `clCreateCommandBufferKHR` should
  be in terms of `cl_khr_command_buffer_multi_device`.
* "New Structure" heading can be deleted as these are listed under
  "New Types"
* Typos in rendering of some types

Author: Ewan Crawford

api/cl_khr_command_buffer.asciidoc

@@ -205,11 +205,6 @@ features:
   ** {clCommandSVMMemcpyKHR}
   ** {clCommandSVMMemFillKHR}
 
-=== New Structures
-
-  * {cl_command_buffer_khr_TYPE}
-  * {cl_mutable_command_khr_TYPE}
-
 === New Types
 
   * {cl_device_command_buffer_capabilities_khr_TYPE}

api/opencl_runtime_layer.asciidoc

@@ -14145,7 +14145,10 @@ returned in _errcode_ret_:
     specified by {CL_DEVICE_COMMAND_BUFFER_REQUIRED_QUEUE_PROPERTIES_KHR}.
   * {CL_INVALID_CONTEXT} if all the command-queues in _queues_ do not have
     the same OpenCL context.
-  * {CL_INVALID_VALUE} if _num_queues_ is zero.
+  * {CL_INVALID_VALUE} if the `<<cl_khr_command_buffer_multi_device>>`
+    extension is supported and _num_queues_ is zero, or if the
+    `<<cl_khr_command_buffer_multi_device>>` extension is not supported
+    and _num_queues_ is not one.
   * {CL_INVALID_VALUE} if _queues_ is `NULL`.
   * {CL_INVALID_VALUE} if values specified in _properties_ are not valid, or
     if the same property name is specified more than once.