Fixed typos in CODE_OF_CONDUCT.md (#490)

Author: HenokB

CODE_OF_CONDUCT.md

@@ -5,7 +5,7 @@
 In the interest of fostering an open and welcoming environment, we as
 contributors and maintainers pledge to making participation in our project and
 our community a harassment-free experience for everyone, regardless of age, body
-size, disability, ethnicity, sex characteristics, gender identity and expression,
+size, disability, ethnicity, sex characteristics, gender identity, and expression,
 level of experience, education, socio-economic status, nationality, personal
 appearance, race, religion, or sexual identity and orientation.