Update gatsby in /docs from 1.9.138 to 1.9.139

[dependencies]

Dependencies.io has updated gatsby (a npm dependency in /docs) from "1.9.138" to "1.9.139".

1.9.139

No content found. Please open an issue at https://github.com/dependencies-io/support if you think this content could have been found.

[codecov]

Codecov Report

Merging #2499 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2499   +/-   ##
=======================================
  Coverage   16.87%   16.87%           
=======================================
  Files         307      307           
  Lines        7792     7792           
  Branches      788      787    -1     
=======================================
  Hits         1315     1315           
- Misses       5822     5862   +40     
+ Partials      655      615   -40

Impacted Files	Coverage Δ
app/vue/src/server/config/babel.js	0% <0%> (-100%)	⬇️
app/vue/src/server/babel_config.js	0% <0%> (-77.42%)	⬇️
lib/ui/src/modules/ui/components/layout/index.js	30.07% <0%> (ø)	⬆️
addons/a11y/src/components/Report/Info.js	0% <0%> (ø)	⬆️
lib/ui/src/modules/ui/components/search_box.js	32.94% <0%> (ø)	⬆️
addons/jest/src/components/Indicator.js	0% <0%> (ø)	⬆️
addons/knobs/src/react/WrapStory.js	19.54% <0%> (ø)	⬆️
app/react/src/client/preview/element_check.js	41.17% <0%> (ø)	⬆️
addons/a11y/src/components/WrapStory.js	0% <0%> (ø)	⬆️
addons/a11y/src/components/Report/Tags.js	0% <0%> (ø)	⬆️
... and 46 more

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