Spelling fixes

Spelling errors found using github.com/lucasdemarchi/codespell
A tool to fix common misspellings.
This tool is licensed under GNU General Public License, version 2.

Change-Id: I8af789c1e0fef9938baced40315b525199636601
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/argument.hpp b/argument.hpp
index f821060..cae4a64 100644
--- a/argument.hpp
+++ b/argument.hpp
@@ -22,7 +22,7 @@
         ArgumentParser(ArgumentParser&&) = default;
         ArgumentParser& operator=(ArgumentParser&&) = default;
 
-        /** @brief Contructs Argument object
+        /** @brief Constructs Argument object
          *
          *  @param[in] argc - the main function's argc passed as is
          *  @param[in] argv - the main function's argv passed as is