chore: update icons to v6 and switch CDNs

[ayuhito]

Sister PR to ionic-team/ionicons#1804, in correspondence to that I've gone ahead and updated the website.

I also updated ionicons to v6 in the process since it seems like the version shown on the website is dependent on the installed version in this repository. Maybe we should look into an alternative solution that updates the versions in the documentation automatically?

Also the diff for index.html exists due to rebuilding the site for v6. Someone may Prettier'd that page by accident in the past since the loss of lines is from:

<symbol id="accessibility" class="ionicon" viewBox="0 0 512 512">
        <title>Accessibility</title>
        <path d="M256 112a56 56 0 1156-56 56.06 56.06 0 01-56 56z" />
        <path
          d="M432 112.8l-.45.12-.42.13c-1 .28-2 .58-3 .89-18.61 5.46-108.93 30.92-172.56 30.92-59.13 0-141.28-22-167.56-29.47a73.79 73.79 0 00-8-2.58c-19-5-32 14.3-32 31.94 0 17.47 15.7 25.79 31.55 31.76v.28l95.22 29.74c9.73 3.73 12.33 7.54 13.6 10.84 4.13 10.59.83 31.56-.34 38.88l-5.8 45-32.19 176.19q-.15.72-.27 1.47l-.23 1.27c-2.32 16.15 9.54 31.82 32 31.82 19.6 0 28.25-13.53 32-31.94s28-157.57 42-157.57 42.84 157.57 42.84 157.57c3.75 18.41 12.4 31.94 32 31.94 22.52 0 34.38-15.74 32-31.94a57.17 57.17 0 00-.76-4.06L329 301.27l-5.79-45c-4.19-26.21-.82-34.87.32-36.9a1.09 1.09 0 00.08-.15c1.08-2 6-6.48 17.48-10.79l89.28-31.21a16.9 16.9 0 001.62-.52c16-6 32-14.3 32-31.93S451 107.81 432 112.8z"
        />
      </symbol>

To

<symbol id="accessibility" class="ionicon" viewBox="0 0 512 512"><title>Accessibility</title><path d="M256 112a56 56 0 1156-56 56.06 56.06 0 01-56 56z"/><path d="M432 112.8l-.45.12-.42.13c-1 .28-2 .58-3 .89-18.61 5.46-108.93 30.92-172.56 30.92-59.13 0-141.28-22-167.56-29.47a73.79 73.79 0 00-8-2.58c-19-5-32 14.3-32 31.94 0 17.47 15.7 25.79 31.55 31.76v.28l95.22 29.74c9.73 3.73 12.33 7.54 13.6 10.84 4.13 10.59.83 31.56-.34 38.88l-5.8 45-32.19 176.19q-.15.72-.27 1.47l-.23 1.27c-2.32 16.15 9.54 31.82 32 31.82 19.6 0 28.25-13.53 32-31.94s28-157.57 42-157.57 42.84 157.57 42.84 157.57c3.75 18.41 12.4 31.94 32 31.94 22.52 0 34.38-15.74 32-31.94a57.17 57.17 0 00-.76-4.06L329 301.27l-5.79-45c-4.19-26.21-.82-34.87.32-36.9a1.09 1.09 0 00.08-.15c1.08-2 6-6.48 17.48-10.79l89.28-31.21a16.9 16.9 0 001.62-.52c16-6 32-14.3 32-31.93S451 107.81 432 112.8z"/></symbol>

It just got rid of the nesting when building.

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Name	Status	Preview	Updated
ionicons-site	✅ Ready (Inspect)	Visit Preview	Jul 13, 2022 at 10:31PM (UTC)