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: I13bbeeb8f1467efc1cf8748e1a66343e879dfc8a
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/lib/open_power_utils.robot b/lib/open_power_utils.robot
index 327b67b..e9dd042 100644
--- a/lib/open_power_utils.robot
+++ b/lib/open_power_utils.robot
@@ -36,7 +36,7 @@
 
 
 Count Object Entries
-    [Documentation]  Count the occurence number of a given object.
+    [Documentation]  Count the occurrence number of a given object.
     [Arguments]  ${object_base_uri_path}  ${object_name}
 
     # Description of argument(s):