Create CONTRIBUTING.md (#244)

* Create CONTRIBUTING.md

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

CONTRIBUTING.md

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+# ESDS Blog Contributors Guide
+
+> **Note**: Steps 1-5 are only necessary the first time; once you have forked and cloned the repo you can start at step 6 to create new branches for new contributions
+
+1. From web, fork the ESDS repo
+    * “Fork” button in upper right
+
+2. From terminal, navigate to where you’d like to clone the repo
+
+3. Clone your fork
+```
+git clone [email protected]:$USER/esds.git
+```
+
+5. Navigate to cloned repo
+```
+cd esds
+```
+
+6. Add upstream to original repo and verify
+```
+git remote add upstream [email protected]:NCAR/esds.git
+git remote -vv
+```
+
+6. Create branch for new blog post and switch to it
+```
+git checkout -b $BRANCH
+git branch -va
+```
+
+7. Set tracking information for the branch
+```
+git branch --set-upstream-to=origin/$BRANCH $BRANCH
+```
+
+9. Add and edit file(s) in the appropriate blog post folder, e.g., /posts/2023/
+    * Tip: look at other posts (.md or .ipynb files) to get ideas on formatting
+    * To add author/date/tags to a notebook post, click on the settings icon in the top right corner of jupyterlab for the first cell of the notebook (use an existing notebook post to see formatting).
+
+10. When ready, add your changes
+```
+git add $FILES
+```
+
+12. Commit your changes
+```
+git commit -m "$MESSAGE"
+```
+
+13. Push your changes to your fork
+```
+git push origin $BRANCH
+```
+
+15. From web, open a pull request from your fork or the main ESDS repo
+    * Github should prompt you to do this with a yellow bar at the top of the screen
+    * Add a title and description to the PR
+    * You can add/edit reviewers using the panel in the top right of the PR
+
+16. The PR may change text/code via auto-fixes from pre-commit hooks that have been set up in the repository. Be sure to pull these changes to your local clone/branch before making additional changes (e.g., as a result of the PR reviews) or you may end up with merge conflicts.
+```
+git pull
+```