chore(AIP-217): fix formatting (#1391)

Author: noahdietz

aip/general/0217.md

@@ -98,14 +98,14 @@ aforementioned guidance i.e. the API call returns an error status instead of a
 partial result, to adopt the `unreachable` pattern the API **must** do the
 following:
 
-  * the default behavior **must** be retained to avoid incompatible behavioral
-    changes
-    * For example, if the default behavior is to return an error if any location
-      is unreachable, that default behavior **must** be retained.
-  * the request message **must** have a `bool return_partial_success` field
-  * the response message **must** have the standard
-    `repeated string unreachable` field
-  * the two aforementioned fields **must** be added simultaneously
+- The default behavior **must** be retained to avoid incompatible behavioral
+  changes
+  - For example, if the default behavior is to return an error if any location
+    is unreachable, that default behavior **must** be retained.
+- The request message **must** have a `bool return_partial_success` field
+- The response message **must** have the standard
+  `repeated string unreachable` field
+- The two aforementioned fields **must** be added simultaneously
 
 When the `bool return_partial_success` field is set to `true` in a request, the
 API **must** behave as described in the aforementioned guidance with regards to