Startup tip fixes

[m-kuhn]

Remove outdated tips and perform some spelling and styling fixes.

[nyalldawson]

@m-kuhn to be honest, I've been wondering whether startup tips have had their time and should be removed. It's quite an outdated approach now and the only other modern software package I see using these is PyCharm.

There's also the risk that these tips often get outdated as they aren't updated when the ui or processes change.

I'd prefer to see the tips removed and instead a "first run" dialog (such as is being worked on by Nathan) used to show a "what's new/changed" slideshow where we highlight any important new features or changes to ui.

What do you think?

[m-kuhn]

I'm also not a huge fan of them.

I think that most tips I read (in all programs) are either stating the obvious or explaining the half of the program I am not interested in.

But the main problem with them is, that they are modal.
Have a look at the bottom of this (github) page for example, which says for me

ProTip! Add .patch or .diff to the end of URLs for Git’s plaintext views.

Might be interesting once in a while.
Writing things like "press F7 to open the side-by-side style dock" are really cool to know and on a startup screen they wouldn't interfere with the workflow.

Still, most information is best offered context-aware (good tooltips, descriptive names, placeholder texts...)

[nyalldawson]

Given that the future of tips are in doubt, I'm closing this PR