Fix typos in security section.
-There are many ways to handle security, authentication and autorization.
+There are many ways to handle security, authentication and authorization.
And it normally is a complex and "difficult" topic.
## OAuth2
-OAuth2 is a specification that defines several ways to handle authentication and autorization.
+OAuth2 is a specification that defines several ways to handle authentication and authorization.
-It is quite an extensive especification and covers several complex use cases.
+It is quite an extensive specification and covers several complex use cases.
It includes ways to authenticate using a "third party".