[spark/en] Add Spark LearnXinYMinutes

[scronge]

Description

This PR adds a guide for Spark to the LearnXinYMinutes documentation.

Checklist

• [x] I solemnly swear that this is all original content of which I am the original author
• [x] Pull request title is prepended with [spark/en]
• [x] Pull request touches only one file (or a set of logically related files with similar changes made)
• [x] Content changes are aimed at intermediate to experienced programmers (this is a poor format for explaining fundamental programming concepts)
• [x] If I've changed any part of the YAML Frontmatter, it is formatted according to CONTRIBUTING.md
  • [x] Yes, I have double-checked quotes and field names!

[scronge]

Hi @adambard . Pull request is ready for review. 🦃 Gobble gobble.