[R] Minor docs updates

[asfimport]

• spelling:
• I think that the words "will is under" in this section might be a typo:
  Special instructions on Linux: You will need to set LD_LIBRARY_PATH to the lib directory that will is under where we set $ARROW_HOME, before launching R and using Arrow.
• The section titled "Troublshooting" is missing an "e" in the title

Reporter: Jonathan Keane / @jonkeane
Assignee: Jonathan Keane / @jonkeane

Related issues:

• [R] [Docs] Add S3 to the cmake flags (is duplicated by)

PRs and other links:

• GitHub Pull Request #10143

_{Note: This issue was originally created as ARROW-12520. Please see the migration documentation for further details.}

[asfimport]

Neal Richardson / @nealrichardson:
Issue resolved by pull request 10143
#10143