fix: CONTRIBUTING.md grammar

[DalpatRathore]

Hello! @anuraghazra
    I have fixed a few grammatical mistakes in CONTRIBUTING.md, I have listed them in bullet points. Please review this contribution.

• Reporting a issue an issue
• If you've added code that should be tested, add some tests' example tests' examples.
• To run & test github-readme-stats you need to follow few a few simple steps :- steps:-
  (make sure you already have a [vercel Vercel](https://vercel.com/) account)
• In the .env file add a new variable named "PAT_1" with your [github Personal access token] [GitHub Personal Access Token](https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token)
• All you need to do is edit [themes/index.js] the [themes/index.js](./themes/index.js) file and add your theme at the end of the file.
• While creating the Pull request to add a new theme don't forget to add a screenshot of how your theme looks, you can also test how it looks using custom url URL parameters like title_color, icon_color, bg_color, text_color, border_color
• How to hide jupyter Jupyter Notebook?
• I could not figure out how to deploy on my own vercel Vercel instance
• Please read all the related issues / comments issues/comments before opening any issues regarding language card stats
• What & why you wanted do you want to add the specific feature
• Additional Context context like images, links to resources to implement the feature etc etc , etc.

Thanks

[vercel]

@DalpatRathore is attempting to deploy a commit to the github readme stats Team on Vercel.

A member of the Team first needs to authorize it.

[codecov]

Codecov Report

Merging #1546 (5644838) into master (f830806) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1546   +/-   ##
=======================================
  Coverage   94.81%   94.81%           
=======================================
  Files          22       22           
  Lines         752      752           
  Branches      205      205           
=======================================
  Hits          713      713           
  Misses         35       35           
  Partials        4        4           

Impacted Files	Coverage Δ
themes/index.js	100.00% <0.00%> (ø)
src/translations.js	81.81% <0.00%> (ø)

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[rickstaa]

@DalpatRathore Merged into the master branch. Thanks a lot for your contribution!