Correcting misspellings

[garcialo]

Went through the *.md files in dexie.js-web/docs and corrected things that I'm pretty confident are misspellings.

• Generally one commit per folder
• Made some minor grammatical changes (e.g. criterion/criteria) and tried to give those their own commits
• Ignored deliberate misspellings (e.g. "thingies")
• Changed "catched" to "caught" to be consistent with similar syntax in the docs (e.g. "throw" verbified as "thrown" and not "throwed")

Hopefully these changes aren't too overwhelming to review.

[dfahlander]

Thanks a lot 💯 🥇 <3!