Specify more VSCode workspace settings

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• Here we add my favorite spell checker extension for VSCode to the recommended workspace extensions and populate the settings.json with some words that the spell checker should ignore. In the future, just use the quick fix Add <word> to workspace settings if the spell checker is not aware of a word. Then don't forget to include the settings.json in your commits.
• I've also added some settings that have proven to be a nice default for other projects. These settings relate to Git as well as the editor itself (showing some rulers). Of course settings like the ruler color are very debatable, this is just a default value that you can for sure overwrite locally if you'd like to. I like to aim for 80 colons and only if necessary surpass it. The editor will wrap every line that is longer than 100 colons (toggle via Alt + Z) just as a visual reminder that this line is probably too long.