Correction of some formatting and image alias errors

I'm not sure where to put this information for now, but here's what I corrected. To be added to some sort of guide later.

• There must be some spaces before the :alt: line, at least so that it lines up with the | above it

  • We use 4 "tabs" (hit the "tab" key four times) by convention and so that it lines up nicely
  • The important part is that it must be more indented than the .. which indicates that what follows in a comment
  • If the :alt: line is less indented than the .. , Sphinx will consider it as normal text (and since the images.rst file is used in all pages, that line of text will appear on all pages)

• When updating screenshots, if we change the alias in the images.rst file (the part inside the vertical bars, i.e. |alias|), it's important to change it in all pages where that image appears

  • Personally, I use the command git grep to find all occurrences of the alias in all the pages. Most images are only used once, but some are used more than once.
  • So if we change |image123|to |something| in images.rst it's important to change |image123| to |something| in every page where that image appears
  • It's important to change the alias in the page for the same alias that is in images.rst. So if we change |image123|to |something| in images.rst it's important to use exactly |something| in the page as well not |image of something| or some other text.

• In images.rst we use the file name as the alias. This is by convention in our project. It makes it easier to remember what the alias is.

The format is

.. |filename| image:: images/directory/filename.png
        :alt: Alternate text

And in the page, the format is

|filename|