fix: Missing "this" in brewery app code

[tinykite]

What this does

Adds a missing "this" to the examples for building a brewery app with Lit:

 ${this.breweries.map(
          brewery => html`
            <li>
              <brewery-template
                .brewery="${brewery}"
                .toggleVisitedStatus=${() => this.toggleVisitedStatus(brewery)}>
              </brewery-template>
            </li>
          `,
        )}

Without it, the example code loads but indefinitely shows "Loading" text instead of the list of Minneapolis breweries. (Which is a lovely sight, as a Minneapolis local!)

[netlify[bot]]

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[tinykite]

Great, happy to suggest it!! Wasn't sure about the deploy issues, so would love a hand there.