3.1.5 release #3596

I made a mistake when aggregating the release notes for the 3.1.4 release, and so the release notes section of the docs incorrectly refers to a 3.14 release. There were other errors in the release notes rendering (thanks to @QuLogic for spotting these), and I also found that the automatically-generated document headings were incorrect (we had multiple h1 headings). These fixes are in #3594

To quickly fix the release notes page, I'd like to quickly release 3.1.5. Does anyone object to this? I know it's Friday, but this release only affects the docs.

@zarr-developers/python-core-devs