chore: Create contributing guidelines

CONTRIBUTING.md

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+# Contributing Guidelines
+
+Your input is amazing! Making contributing to this project as easy and transparent as possible is one of the most important side, this includes:
+
+- Discussing the current state of the wordlists
+- Submitting new wordlists
+- Proposing new words into existing wordlists
+- Becoming a maintainer
+
+## Wanted changes
+
+- New wordlists
+- Fixing of spelling and grammatical mistakes, in Markdown files
+
+## Unwanted changes
+
+- Whitespaces and punctuation changes
+- Word changes using synonyms
+- Entire rewrites of the project, or parts of the project - unless approved first by a maintainer
+- The addition of very few words to existing wordlists, this will depend on the wordlist.
+    - They will still be merged, but try to make a bigger contribution, maybe to some other wordlist or you may find more additions online.
+
+## All changes happen through pull requests
+
+Pull requests are the best way to propose changes. We actively welcome your pull requests:
+
+1. Fork the repo and create your branch from `main`.
+2. Keep consistency with the current state of the wordlists, this includes:
+    - The naming convention of the files are **always** `snake_case`.
+    - The wodlists **must** be sorted using [this website](https://appdevtools.com/sort-lines) and its default settings.
+    - There must be **no** empty lines.
+    - All wordlists are **lowercase** unless it makes sense, e.g. file names.
+    - For wordlists for names, cities, countries, etc. **every word** must be capitalized. (e.g. **J**ohn **C**ena, not John **c**ena or **j**ohn **c**ena)
+3. Issue that pull request!
+
+## Commit messages guidelines
+
+This project uses [`Conventional Commits 1.0.0`](https://conventionalcommits.org/en/v1.0.0/) hence your commit messages **must** follow the same convention or your contributions will be ignored, refused or assigned to another user or maintainer. For commits regarding addition to wordlists, etc. we use the commit messages like **`wordlist(file_name): Add three new words`**.
+
+It would be more than welcome to keep your contributions as a single commit rather than, for examples, 20 `"wordlist(whatever): Add new word"` commits in-between. You may use multiple commmits if you believe the changes made in these commmits have nothing, or close to nothing, in common - feel free to ask a maintainer on whether or not it should be a single commit or not.