fixed some typos.

Author: mshindo

switch.rst

@@ -255,7 +255,7 @@ developers implementing forwarding programs like ``forward.p4`` with
 an abstract target machine, analogous to a Java Virtual Machine. The
 goal is the same as for Java: to support a *write-once-run-anywhere*
 programming paradigm. (Note that :numref:`Figure %s <fig-psa>`
-includes the generic ``arch.p4`` as the the architecture model spec,
+includes the generic ``arch.p4`` as the architecture model spec,
 but in practice the architecture model would PSA specific, such as
 ``psa.p4``.)
 
@@ -265,7 +265,7 @@ but in practice the architecture model would PSA specific, such as
     :align: center
 
     P4 architecture known as the Portable Switch Architecture
-    (PSA). Includes the generic ``arch.p4`` as the the architecture
+    (PSA). Includes the generic ``arch.p4`` as the architecture
     model spec, but for PSA this would be replaced by ``psa.p4``.
 
 When compared to the simpler PISA model used in :numref:`Figure %s

trellis.rst

@@ -221,7 +221,7 @@ Plane Manager) is yet
 another ONOS Service–one of the Trellis suite of services. Its
 job is to learn routes from external sources, which it does by tapping
 into a locally running Quagga process that is configured to peer with
-BGP neighbors. Whenever FPM learns about an external route, is adds
+BGP neighbors. Whenever FPM learns about an external route, it adds
 the corresponding prefix-to-nexthop mapping to the Route service,
 indicating that the destination prefix is reachable via the leaf
 switches that connect the fabric to upstream networks (e.g., Switches 3