docs: vendor-ibm-astlpc: Use numbered list for strictly ordered ops

I'm not sure how we used a bullet list for a section titled "the
following sequence occurs".

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I28dbe579de62a77726c617dd7aad11239a23f2ff
diff --git a/docs/bindings/vendor-ibm-astlpc.md b/docs/bindings/vendor-ibm-astlpc.md
index e0cdd80..98634c8 100644
--- a/docs/bindings/vendor-ibm-astlpc.md
+++ b/docs/bindings/vendor-ibm-astlpc.md
@@ -290,12 +290,12 @@
 
 During packet transmission, the follow sequence occurs:
 
-* The Tx side writes the packet to its Tx buffer
-* The Tx side sends a `Tx Begin` message, indicating that the buffer ownership
-  is transferred
-* The Rx side now owns the buffer, and reads the message from its Rx area
-* The Rx side sends a `Rx Complete` once done, indicating that the buffer
-  ownership is transferred back to the Tx side.
+1. The Tx side writes the packet to its Tx buffer
+2. The Tx side sends a `Tx Begin` message, indicating that the buffer ownership
+   is transferred
+3. The Rx side now owns the buffer, and reads the message from its Rx area
+4. The Rx side sends a `Rx Complete` once done, indicating that the buffer
+   ownership is transferred back to the Tx side.
 
 ### LPC Binding Operation