fix misspelling
fix misspelling in memory management doc
@@ -517,7 +517,7 @@ Trusty
For an Android User OS, there is a secure world named trusty world
support, whose memory must be secured by the ACRN hypervisor and
-must not be accessible by the Seervice/User VM normal world.
+must not be accessible by the Service/User VM normal world.
.. figure:: images/mem-image18.png
:align: center
