docs: streamline README and reorganize v1.1 documentation (#306)

CONTRIBUTING.md

@@ -19,11 +19,60 @@ Pull requests are the best way to propose changes to the codebase. We actively w
 4. Ensure the test suite passes.
 5. Issue that pull request!
 
+## Development
+
+Install dependencies:
+
+```bash
+poetry install -E async
+```
+
+Offline tests are deterministic and should run before every pull request:
+
+```bash
+poetry run pytest \
+  tests/ \
+  --ignore=tests/external_tests
+```
+
+External tests contact the live MLB API. They require internet access and are separate from normal offline CI:
+
+```bash
+poetry run pytest \
+  tests/external_tests/
+```
+
+These live tests may fail because the MLB service is unavailable or because MLB changes undocumented payloads.
+
+Full local validation:
+
+```bash
+poetry run pytest tests/
+rm -rf dist
+poetry build
+python3 scripts/validate_release.py
+poetry run twine check dist/*
+```
+
+`scripts/validate_release.py` is the same release check offline CI runs. It inspects the built wheel and source distribution, clean-installs each artifact into its own temporary virtual environment, and runs the same public-API smoke test against both installed artifacts. Every response it observes comes from injected fake HTTP clients, so it never contacts the MLB API.
+
+Offline CI is the normal pull-request gate. External tests are available manually, on a weekly schedule, and before releases.
+
+## Pull Request Guidelines
+
+- Run offline tests before submitting a PR
+- Use the [PR template](.github/pull_request_template.md) when creating your pull request
+- Follow the branch naming convention:
+  - `feat/` - New features
+  - `fix/` - Bug fixes
+  - `docs/` - Documentation updates
+  - `refactor/` - Code improvements
+
 ## Any contributions you make will be under the MIT Software License
 In short, when you submit code changes, your submissions are understood to be under the same [MIT License](http://choosealicense.com/licenses/mit/) that covers the project. Feel free to contact the maintainers if that's a concern.
 
 ## Report bugs using Github's [issues](https://github.com/zero-sum-seattle/python-mlb-statsapi/issues)
-We use GitHub issues to track public bugs. Report a bug by [opening a new issue](); it's that easy!
+We use GitHub issues to track public bugs. Report a bug by [opening a new issue](https://github.com/zero-sum-seattle/python-mlb-statsapi/issues/new).
 
 ## Write bug reports with detail, background, and sample code
 **Great Bug Reports** tend to have:
@@ -37,7 +86,7 @@ We use GitHub issues to track public bugs. Report a bug by [opening a new issue]
 - Notes (possibly including why you think this might be happening, or stuff you tried that didn't work)
 
 ## Use a Consistent Coding Style
-* Adhere to this projects coding style
+* Adhere to this project's coding style
 
 ## License
-By contributing, you agree that your contributions will be licensed under its MIT License.
+By contributing, you agree that your contributions will be licensed under its MIT License.