Add explanation to what the changed files icons/annotation mean

[sofiahe]

In the Changed file section and push window the changed files as a icon, depending on what changes has been made to the file. The icons are not explained anywhere.

Maybe add a hoover or documentation for them.

[AGulev]

@erikangelin-king here we have documentation https://www.defold.com/manuals/workflow/#_your_local_working_copy