docs: improve presentation of contributing guidelines

[rich-iannone]

This addresses a number of pyOpenSci reviewer comments related to contributing guidelines.

One comment involves putting the contributing guidelines on the Great Tables website. That is done here and the link to the page is presented on the top navbar.

Fixes: #544

Another useful recommendation was to link to the Stack Overflow guide on creating a minimal reproducible example (MRE). This was done in CONTRIBUTING.md

Fixes: #532

A comment noted that a CONTRIBUTING.md file exists but it is not linked to from README.md. We agree that this makes the information hard to find while on GitHub. Here, CONTRIBUTING.md is moved to the top-level dir (like Polars and Rich repos do). This makes it easier to link to from the README (and there is no special purpose for CONTRIBUTING.md to be with the .github directory, unlike other files in there). The Contributing to Great Tables section was added near the bottom of README.md and the link to CONTRIBUTING.md was included in there.

Fixes: #527

Another comment was focused on including more contributor onboarding guidelines of the following nature:

• explicitly list the requirements for a submission to be considered (e.g. code style, formatting, having tests covering the new feature/preventing a regression on a bug fix) and the make command associated
• include the command to create a virtual environment with the development dependencies
• guide new contributors to using pre-commit.

New sections have been added to CONTRIBUTING.md: Setting Up Your Development Environment, Building the Documentation Locally, and Running Tests Locally. This covers the recommendations for improved onboarding directions.

Fixes: #534

A comment brought up the usefulness of mentioning how to install the package in editable mode. In addition, documenting the [all] and [dev] install options would be useful.

This has been added to CONTRIBUTING.md in the new Setting Up Your Development Environment section.

Fixes: #543

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.79%. Comparing base (925fa41) to head (8d715b1).
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #550   +/-   ##
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  Coverage   89.79%   89.79%           
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  Files          45       45           
  Lines        5321     5321           
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  Hits         4778     4778           
  Misses        543      543           

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[machow]

Would it be okay if we move this page to the guide (say in a bottom section called extra "Extra")? I think at some point it might be worth having a Community tab, but it seems useful top keep the top bar light, and thicken up the guide right now

(Feel free to merge right away with it in the guide)