feat(scope): allow filtering patterns when updating cache on autocmd events

[Subjective]

• feat(scope): allow filtering patterns when updating cache on autocmd events
• docs: add example of updating scope on autocmd event with pattern

[cbochs]

Instead of having to parse the cache it could be a table like so?

cache = {
    event = "User",
    pattern = "PluginEvent"

[cbochs]

Thank you for the PR! Going to close as #89 addresses these changes