Check that all tutorials follow the Contributing document standards

[eblur]

We will check that all tutorials follow the standard template in the Contributing documentation

• Does the header conform to the template? If not, modify it.
• Does the tutorial follow the general guidelines with respect to voice, clarity, and using descriptive headers? If not, how would you modify it?

First set of tutorials to go through:

• Modifying a FITS header
• FITS tables
• FITS images