MINOR: [R] Fix typo in installation vignette

[tdhock]

Rationale for this change

What changes are included in this PR?

Are these changes tested?

Are there any user-facing changes?

[github-actions]

Thanks for opening a pull request!

If this is not a minor PR. Could you open an issue for this pull request on GitHub? https://github.com/apache/arrow/issues/new/choose

Opening GitHub issues ahead of time contributes to the Openness of the Apache Arrow project.

Then could you also rename the pull request title in the following format?

GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

or

MINOR: [${COMPONENT}] ${SUMMARY}

In the case of PARQUET issues on JIRA the title also supports:

PARQUET-${JIRA_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

See also:

• Other pull requests
• Contribution Guidelines - How to contribute patches

[thisisnic]

Well spotted, thanks!

[ursabot]

Benchmark runs are scheduled for baseline = 5bb2111 and contender = 013de75. 013de75 is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Finished ⬇️0.0% ⬆️0.0%] ec2-t3-xlarge-us-east-2
[Finished ⬇️3.57% ⬆️0.03%] test-mac-arm
[Finished ⬇️0.51% ⬆️0.0%] ursa-i9-9960x
[Finished ⬇️0.57% ⬆️0.06%] ursa-thinkcentre-m75q
Buildkite builds:
[Finished] 013de752 ec2-t3-xlarge-us-east-2
[Finished] 013de752 test-mac-arm
[Finished] 013de752 ursa-i9-9960x
[Finished] 013de752 ursa-thinkcentre-m75q
[Finished] 5bb21117 ec2-t3-xlarge-us-east-2
[Finished] 5bb21117 test-mac-arm
[Finished] 5bb21117 ursa-i9-9960x
[Finished] 5bb21117 ursa-thinkcentre-m75q
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java