Disabling autocompletion in comments

When writing comments in Lua, the autocompletion suggests words while typing. This happens without a delay and after typing the first letter of a word. I found the quickly flashing suggestions very distracting and wanted to disable them.

I assumed that I could change this in the Lua section in the settings, and tried this:

```
"Lua.completion.enable": false,
"Lua.completion.showWord": "Disable",
"Lua.completion.workspaceWord": false,
```

This didn't fix the issue, and I still saw the suggestions.

I opened an issue here: https://github.com/LuaLS/lua-language-server/issues/2988

As noted in a comment on that issue, vscode-lua overrides the `editor.quickSuggestions` setting. This was unexpected to me. It would be helpful if this could be changed or documented.

Start by reviewing the VSCode extension settings behavior that overrides editor.quickSuggestions, using the linked LuaLS issue #2988 for context. Done means users can disable comment autocompletion as expected, or the override and available configuration are clearly documented.

Written by the indexing model from the issue text.