Correct two spelling mistakes in Neutron devrefs

Change-Id: Ia15c82363972845c70e773d85aa3be3beb2e0eb5

doc/source/devref/callbacks.rst

@@ -65,7 +65,7 @@ do whatever they are supposed to do. In a callback-less world this would work li
   # A gets hold of the references of B and C
   # A calls B
   # A calls C
-  B->my_random_method_for_knowning_about_router_created()
+  B->my_random_method_for_knowing_about_router_created()
   C->my_random_very_difficult_to_remember_method_about_router_created()
 
 If B and/or C change, things become sour. In a callback-based world, things become a lot

doc/source/devref/neutron_api.rst

@@ -2,7 +2,7 @@ Neutron public API
 ==================
 
 Neutron main tree serves as a library for multiple subprojects that rely on
-different modules from neutron.* namespace to accomodate their needs.
+different modules from neutron.* namespace to accommodate their needs.
 Specifically, advanced service repositories and open source or vendor
 plugin/driver repositories do it.