Fix typo on marketplace design code sample

[javiermanzano]

Description

There is a typo on marketplace sample documentation. Balance for the second account is not correct (it's working fine on the playground)

---

• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[turbolent]

Thank you!

[codecov-commenter]

Codecov Report

Merging #1207 (ea5cd9d) into master (23a917f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1207   +/-   ##
=======================================
  Coverage   73.39%   73.39%           
=======================================
  Files         272      272           
  Lines       34603    34603           
=======================================
  Hits        25398    25398           
  Misses       8032     8032           
  Partials     1173     1173           

Flag	Coverage Δ
unittests	73.39% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 09e67f9...ea5cd9d. Read the comment docs.