Fix various grammar/typos in "Fundamentals" documents

[ncurrault]

I noticed these when learning about Sigma:

• Fundmentals 1
  • "it's release" (wrong "its")
  • "we can the default account types" (added missing word)
• Fundmentals 2
  • "excel/google sheets" (capitalization)
• Fundmentals 4
  • "(ie: write the function for you!)" (punctuation for "i.e." abbreviation)
  • "4.5+ record PLUGS_DATA table" (the table contains 4.5 million records, not just 4.5)
• Fundmentals 6
  • "ensure this, of you don't" (misspelling)
• Fundmentals 8
  • "joins effects" (wrong "affect"; subject-verb agreement)
  • "Linage" (misspelling)
  • "They are not stored in your cloud data warehouse or effect your source data in any way." (wrong "affect"; parallel structure)
  • "you have need more information" (unnecessary word)
  • "it's format" (wrong its)

[pballai]

Thank you for your attention to detail Nickolas.