[Docs] Add Docker COPY from Example about pgvector

[jkatz]

If this is targeted for a production build, I'd recommend just installing pgvector from a package into the container image. I checked the upstream PostgreSQL repos, and both yum and apt include pgvector.

[ankane]

Hi @yordis, feel free to share if you get this working. You can see which files pgvector installs by looking at the output of make install.

[yordis]

@jkatz I ended up just using apt, but I wish it happened across the ecosystem to be able to pull from another Docker Image into the base one. Not everyone is publishing, but I found they mainly provide Docker images.

Imagine the following as a standard:

FROM postgres:16-bookworm

COPY --from=pgvector/pgvector:0.6.2-extension /PGEXTENSION/${PG_MAJOR} /

That tree under /PGEXTENSION has ONLY the files required to copy into my image, making it safe to copy everything from it into the / safely.