Docs/small improvements to the rust doc landing page

[SimonSchneider]

fixes #4432

also included some other small improvements to the landing page docs as separate commits so they can be removed if they are unwanted

[SimonSchneider]

Regarding the jemalloc and mimalloc addition, I included it because we saw huge memory improvements when switching to jemalloc.
It resolved two major problems we saw with mimalloc, it seemed to have a much larger memory footprint and it seemed to never release memory back to the OS which in our long running applications caused memory to grow forever.

[ritchie46]

It resolved two major problems we saw with mimalloc, it seemed to have a much larger memory footprint and it seemed to never release memory back to the OS which in our long running applications caused memory to grow forever.

I shared that experience, but didn't the memory saturate at one point? E.g. reaching an asymptote.

[SimonSchneider]

I would have though so as well but that was not the case. This graph is memory usage over a month for a 32Gb instance. Not optimal but it has not caused major headaches as memory grows slowly and we have been ok with the fact that an OOM crash and restart is a reasonable way of reclaiming memory

same graph over 1 day with jemalloc (Load is of course different but just the fact that memory usage is able to go down is positive)

[SimonSchneider]

I will evaluate how jemalloc performs over a longer time period but initially it looks promising. I can report back in a month or so with some insights.

[ritchie46]

I would have though so as well but that was not the case. This graph is memory usage over a month for a 32Gb instance. Not optimal but it has not caused major headaches as memory grows slowly and we have been ok with the fact that an OOM crash and restart is a reasonable way of reclaiming memory

Interesting. I wonder if we can modify the mimalloc settings to prevent this.