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: I4f11e1fbf3f74e63787b15a126de0e68e5266036
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/src/sdeventplus/exception.hpp b/src/sdeventplus/exception.hpp
index 697ccb1..1303062 100644
--- a/src/sdeventplus/exception.hpp
+++ b/src/sdeventplus/exception.hpp
@@ -14,7 +14,7 @@
   public:
     /** @brief Creates a new SdEventError from error data
      *
-     * @param[in] r      - The postive errno code
+     * @param[in] r      - The positive errno code
      * @param[in] prefix - The prefix string to display in the what()
      */
     SdEventError(int r, const char* prefix);