Validate that GAP directories only contain allowed files (#35)

Adds a file allowlist check to validate-structure.js — GAP directories may now only contain *.md files and metadata.yml. Rejects unexpected files or subdirectories with a message pointing contributors to @graphql/gaps-editors.

Motivation: prevent files like .nvmrc from being merged that could inadvertently affect developer environments.

GraphQL Auxiliary Proposals (GAPs)

This repository provides a public home for GraphQL Auxiliary Proposals (GAPs), community specifications and auxiliary proposals that address issues outside of the core GraphQL spec.

This repository is not generally intended for custom scalar specifications, which already have dedicated homes elsewhere.

Visit the website

This repository is not designed to be browsed directly; please instead visit the website which automatically renders each specification via spec-md and includes additional navigational assistance and cross-linking:

https://gaps.graphql.org/

GAP Numbering

Each GAP is numbered after the GitHub Pull Request that introduces it. For example, if the PR that adds a GAP is graphql/gaps#10, the proposal becomes GAP-10.

Repository structure

Each proposal lives in its own GAP-N folder and must include:

DRAFT.md — the working document of the proposal/specification
README.md — a brief overview and status, including challenges/drawbacks and related resources or prior art
metadata.yml — summary, authorship, sponsorship, status, and related metadata

See CONTRIBUTING.md for the full GAP process.