tutorial: Sync doc link with gstreamer crates
I wasn't sure that the tutorial had intended to link to slomo's freedesktop uri, but I guessed that it might be good to sync to the page on GStreamer rust crates which normally can search via crates.io.
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I wasn't sure that the tutorial had intended to link to slomo's freedesktop uri, but I guessed that it might be good to sync to the page on GStreamer rust crates which normally can search via crates.io.