Update refdocs to use markdown links and standardize HTTP/2 notation in master

[AdeshGhadage]

Converted inline URLs to markdown format in refdocs. Standardized "HTTP2" to "HTTP/2". Changes made in the master branch of istio/api. This aligns with issue #16102.

[istio-policy-bot]

😊 Welcome @AdeshGhadage! This is either your first contribution to the Istio api repo, or it's been
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[istio-testing]

Hi @AdeshGhadage. Thanks for your PR.

I'm waiting for a istio member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[zirain]

/ok-to-test

[craigbox]

Please bring the URL changes from #3431 into this PR and we can proceed. Check each URL, as the first one I tried was 404.

[craigbox]

Looking good.
You can add the "release-notes-none" label for this as nothing you have changed requires a release note entry.

[AdeshGhadage]

I think i don't have permission to add label "release-notes-none"

[craigbox]

/release-note-none

(I understand the commands that are listed here, apparently)

[AdeshGhadage]

/release-note-none

[zirain]

/test release-notes

[craigbox]

(someone should raise an issue that the bot should have done this)