Adds a new `reference/` path that centralizes the logic for creating
reference documentation
## For Python
We can leverage the existing reference docs pipeline thats used within
the `langchain` repo, and adapting it to include docs from more sources
(see https://github.com/langchain-ai/langchain/pull/33066). More details
about how this works are in `reference/python/README.md`.
## For TypeScript
We'll be keeping the existing [typedoc](https://typedoc.org/) library to
render references, but we're onshoring the work of consolidating those
into one reference site within this repo.
The basic process of how that happens is:
* by reading a statically defined list of packages and their locations
(defined in reference/javascript/build.ts`)
* doing a shallow clone of each unique repo + branch
* doing the appropriate install steps so that types can be inferred
properly
* extracting package entrypoints by reading the `exports` key in
`package.json`
* pointing typedoc to add those as entrypoints with the [packages
strategy](https://typedoc.org/documents/Options.Input.html#packages)
* building the typedoc outputs to reference/dist/javascript/
## New `make` targets
- `make build-references` will run scripts to format python + js
reference documentation concurrently (which will end up in
reference/dist/)
- `make preview-references` will run aforementioned build scripts and
start a dev server (this won't work until a vercel project is
configured)
## Vercel Setup
In order for these changes to be reflected on `reference.langchain.com`,
a new Vercel project needs to be created (which can happen once this is
merged).
This was tested against a "test" vercel setup and works as expected,
with both reference targets accessible from their respective subpaths
Mason Daugherty