Improve and fix wording in MPS reader documentation

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/library/mps_reader.c b/library/mps_reader.c
index 53a9072..6fda740 100644
--- a/library/mps_reader.c
+++ b/library/mps_reader.c
@@ -43,8 +43,9 @@
  * and significantly increases the C-code line count, but
  * should not increase the size of generated assembly.
  *
- * This reason for this is twofold:
+ * The reason for this is twofold:
  * (1) It will ease verification efforts using the VST
+ *     (Verified Software Toolchain)
  *     whose program logic cannot directly reason
  *     about instructions containing a load or store in
  *     addition to other operations (e.g. *p = *q or