Fixed several minor mistakes in the tutorial 1-2.

Details:
(1) Minor error in the path to the first data tracker.
(2) index.rst don't exist. Use contents.rst instead.
(3) Added instruction on how to add a link into the contents.rst.
(4) Missing :file: directive for some files.
(5) Fixed some unbalanced quotation marks, and some strange quotation marks.
Merge pull request #2 from Tim-HU/squashMultipleCommits

Fixed several minor mistakes in the tutorial 1-2.