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: I9f3925794f1a6318f1ec5172c2d10e18e9aedfa6
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/argument.hpp b/argument.hpp
index 28b2966..9c91615 100644
--- a/argument.hpp
+++ b/argument.hpp
@@ -21,7 +21,7 @@
         ArgumentParser(ArgumentParser&&) = default;
         ArgumentParser& operator=(ArgumentParser&&) = default;
 
-        /** @brief Contructs Argument object
+        /** @brief Constructs Argument object
          *
          *  @param argc - the main function's argc passed as is
          *  @param argv - the main function's argv passed as is