Template update

[flicstar]

Removed the uDig content. Made changes in line with my learnings so far and now it should be a companion to the wiki page: https://trac.osgeo.org/osgeolive/wiki/How%20to%20document%20the%20quickstart%20file

[flicstar]

Updated after reading @camerons review on the 'How to' page of the wiki

[camerons]

Minor comments to be addressed separately to this pull request:

• Inconsistent use of "Quickstart and Quick Start". To date, we have mostly been using "Quickstart"
• When I run "make" in OSGeoLive docs, the _template_quickstart is not being created as HTML, so I can't see the created template as HTML. Ideally, we should be able to see it. I think this might require adding the _template to the projects.csv file, (which likely has bad side effects, like the template might become a full project). Something to discuss later.
• It is hard to find how to build the OSGeoLive docs from our wiki: https://trac.osgeo.org/osgeolive/wiki . Details are found in git: https://github.com/OSGeo/OSGeoLive-doc . This is something to update as a link in our wiki pages.
• Re: "Writing Tip: Optionally, include a screenshot here of the UI."
  ** I don't consider images as Optional. While we don't need one for every step, we do need as many images as the user is about to experience. A user should be able to read the quickstart without running it, and understand from the screenshots what would have happened if running themselves.
  ** Suggest expand accronyms like "UI" to User Interface.