Update link for the sigil_H/2 hex documentation

[sabit990928]

This PR introduces the following: Updates link to liveview hex documentation: https://hexdocs.pm/phoenix_live_view/Phoenix.Component.html#sigil_H/2. So it's not tied to specific version and shows major version page, which is usually fresh, this way newcomers won't be confused by seeing some of the deprecated functions if they will find anything helpful in docs.