added more slides and corrected a typo

lectures/revealjs/07-documentation.adoc

@@ -29,6 +29,8 @@ IT1901 Fall 2019 - 7th Lecture
 - a way to ensure software quality
 - several levels of documentation
 
+[.smaller-60]
+Note: In IT1901 we also look if the documentation is original. You should not just copy paste the documentation from the examples and just rename things to match your project.  
 
 == Types of documentation
 
@@ -63,7 +65,7 @@ IT1901 Fall 2019 - 7th Lecture
 
 == Comments (1)
 
-- allow adding documentatio in close proximity with the code
+- allow adding documentation in close proximity with the code
 - they should not be a way to cope with bad naming or "special" assumptions in the code
 - the standardized comments such as JavaDoc allow  additional benefits such as code completion
 
@@ -137,6 +139,12 @@ https://www.markdownguide.org/basic-syntax
 
 https://gitlab.stud.idi.ntnu.no/help/user/markdown
 
+== Why text based documentation
+
+- it is easier to modify and we do not need any special editors
+- it can be versioned same way as the code
+- holding  documentation in the repository and updating it will allow consulting the repository contents with the correct documentation for that snapshot in time
+
 ++++
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