Update array syntax in website vignette

[andrjohns]

Submission Checklist

• Run unit tests
• Declare copyright holder and agree to license (see below)

Summary

Minor update to array syntax in website OpenCL vignette

Copyright and Licensing

Please list the copyright holder for the work you are submitting
(this will be you or your assignee, such as a university or company):
Andrew Johnson

By submitting this pull request, the copyright holder is agreeing to
license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

[codecov-commenter]

Codecov Report

Merging #841 (0ddbe94) into master (444a5e4) will decrease coverage by 0.03%.
The diff coverage is n/a.

❗ Current head 0ddbe94 differs from pull request most recent head 2709bb1. Consider uploading reports for the commit 2709bb1 to get more accurate results

@@            Coverage Diff             @@
##           master     #841      +/-   ##
==========================================
- Coverage   88.40%   88.38%   -0.03%     
==========================================
  Files          12       12              
  Lines        4201     4201              
==========================================
- Hits         3714     3713       -1     
- Misses        487      488       +1     

see 1 file with indirect coverage changes

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[jgabry]

Good catch, thanks