docs: add contributing.md

Author: adelsz

CONTRIBUTING.md

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+#  Contributing to pgTyped
+
+pgTyped is an open source project, and we welcome contributions of all kinds, including bug reports, feature requests, and pull requests.
+
+# How to contribute?
+
+Our rules for pull requests and issues are fairly standard and flexible. When submitting a change, please provide a brief and descriptive title, if possible written in the imperative mood.
+
+If you have an idea for a new feature or want to address a bug, it's recommended that you first open an issue. We're available to assist and discuss the process of opening a pull request to ensure your changes are incorporated.
+
+We highly recommend you include a test-case added to the `packages/example` project when you submit a pull request or an issue.
+
+This will help us verify your issue or pull request and prevent regressions in the future.
+
+# Development Setup
+
+To get started, clone the repository and install the dependencies:
+
+```bash
+git clone [email protected]:adelsz/pgtyped.git
+cd pgtyped
+npm install
+```
+
+We use a mono-repo setup with [Lerna](https://lernajs.io/) and NPM workspaces.
+This means that running `npm install` will install all the dependencies for all the packages in the project.
+It will also link the packages together, so that you can make changes to one package and immediately see the effects in another package.
+
+The `packages` directory contains the source code for the various components of pgTyped:
+
+- `packages/cli` - The CLI tool for generating TypeScript types from SQL files
+- `packages/wire` - The pgTyped PostgreSQL wire protocol implementation
+- `packages/parser` - The pgTyped SQL and TS language parser
+- `packages/runtime` - The pgTyped runtime library that provides the `sql` template tag and the `sql` function for executing queries.
+- `packages/query` - This package contains higher level PostgreSQL protocol utilities for describing query types, SSL support, and more.
+- `packages/example` - This repository contains a simple example of a pgTyped project written as a Jest test suite. We use this project both as a demonstration of pgTyped and as an end-to-end test suite for the project.
+
+To build the project, run:
+
+```bash
+npm run build
+```
+
+This will build all the packages in the project. To run build in watch mode, run:
+
+```bash
+npm run watch
+```
+
+To run the tests, run:
+
+```bash
+npm test
+```
+
+It will run the tests for all the packages in the project, including end-to-end tests for the example project.
+
+# The `packages/example` project
+
+The `packages/example` project is an end-to-end test suite for pgTyped. It contains a simple example of a pgTyped project written as a Jest test suite.
+
+The packages `npm test` runs the following command:
+
+```bash
+docker-compose run build && docker-compose run test && docker-compose run test-cjs
+```
+
+As you can see it runs the `build` target, then runs the `test` target twice, once with the `esm` module format and once with the `cjs` module format:
+- The `build` target runs pgTyped on the `sql` files in the `packages/example/src` directory generating the query code and type definitions. It also runs `git diff` to verify that the generated code matches the code in the repository.
+- The `test` target runs the queries in `packages/example/src/index.ts` and verifies that the results match the expected results.
+- The `test-cjs` target runs the same tests as the `test` target, but using the `cjs` module format to verify that the generated code works with both module formats.
+
+All the targets are run in a Docker container, with a Postgres database running in a separate container spun up by Docker Compose.
+
+The definitions of each of these targets and the DB service can be found in the `packages/example/docker-compose.yml` file.
+
+The database is initialized with the `sql/schema.sql` file.