Add first-timers.md file for newcomers

[ely-alamillo]

Closes #101

Checklist

• I have made a material change to the repo (functionality, testing, spelling, grammar)
• I have read the [Contribution Guide] and my PR follows them.
• I updated my branch with the master branch.
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation about the functionality in the appropriate .md file
• I have added in line documentation to the code I modified

Short description of what this PR does:

• This PR adds a first-timers.md with a guideline to help new comers.

[SendGridDX]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #104 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #104   +/-   ##
=======================================
  Coverage   91.61%   91.61%           
=======================================
  Files           6        6           
  Lines         298      298           
=======================================
  Hits          273      273           
  Misses         25       25

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b2a3ba0...0cb06e7. Read the comment docs.

[thinkingserious]

Hello @ely-alamillo,

Thanks again for the PR!

It's HACKTOBERFEST! We want to show our appreciation by sending you some special Hacktoberfest swag. If you have not already, could you please fill out this form so we can send it to you? Thanks!

Team SendGrid DX

[thinkingserious]

Hello @ely-alamillo,

Thanks again for the PR!

We noticed that you have earned 3 out of the 5 points needed to receive glorious SendGrid Hacktoberfest swag.

Please take a moment to checkout this link to find more issues to get you past the required threshold.

Also, please be sure that you have officially registered here.

Thank you and Happy Hacktobering!

Team SendGrid DX

[thinkingserious]

Hello @ely-alamillo,

Thanks again for the PR!

You have earned 3 out of the 5 points needed to receive glorious SendGrid Hacktoberfest swag.

Please take a moment to checkout this link to find more issues to get you past the required threshold or to simply continue the celebration.

Also, please be sure you have officially registered with us here by November 1, 2018 to qualify.

If you have any questions you can email us at [email protected].

Thank you and Happy Hacktobering!

Team SendGrid