Minor changes to documentation and comments

Fix some typos and clarify some sentences.

Change-Id: Id276d1ced9a991b4eddc5c47ad9a825e6b29ef74
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/docs/sdei.rst b/docs/sdei.rst
index 531145f..c524817 100644
--- a/docs/sdei.rst
+++ b/docs/sdei.rst
@@ -142,7 +142,7 @@
 .. __: `Defining events`_
 
 -  ``SDEI_MAPF_DYNAMIC``: Marks the event as dynamic. Dynamic events can be
-   bound to (or released from) any Non-secure interrupt at runtime via. the
+   bound to (or released from) any Non-secure interrupt at runtime via the
    ``SDEI_INTERRUPT_BIND`` and ``SDEI_INTERRUPT_RELEASE`` calls.
 
 -  ``SDEI_MAPF_BOUND``: Marks the event as statically bound to an interrupt.
@@ -226,7 +226,7 @@
 Typically, an SDEI event dispatch is caused by the PE receiving interrupts that
 are bound to an SDEI event. However, there are cases where the Secure world
 requires dispatch of an SDEI event as a direct or indirect result of a past
-activity, viz. receiving a Secure interrupt or an exception.
+activity, such as receiving a Secure interrupt or an exception.
 
 The SDEI dispatcher implementation provides ``sdei_dispatch_event()`` API for
 this purpose. The API has the following signature: