[Documentation] Corrected the indentation for code sample.

[debashisdeb]

Corrected the indentation for the code sample, due to which it was not showing up correctly in the documentation.
Have tested locally as well. Attaching images for before and after.

[debashisdeb]

[codecov]

Codecov Report

Merging #3030 (55918c5) into master (ca2e1a6) will decrease coverage by 0.00%.
The diff coverage is 25.80%.

@@             Coverage Diff              @@
##             master    #3030      +/-   ##
============================================
- Coverage     41.55%   41.54%   -0.01%     
- Complexity     4632     4653      +21     
============================================
  Files           595      596       +1     
  Lines         39846    39999     +153     
  Branches       4633     4649      +16     
============================================
+ Hits          16557    16619      +62     
- Misses        21904    22005     +101     
+ Partials       1385     1375      -10     

Impacted Files	Coverage Δ
az-core/src/main/java/azkaban/Constants.java	21.42% <ø> (ø)
.../src/main/java/azkaban/metrics/MetricsManager.java	45.45% <0.00%> (-4.55%)	⬇️
...an/executor/container/ContainerCleanupManager.java	40.00% <0.00%> (-2.70%)	⬇️
...a/azkaban/metrics/ContainerizationMetricsImpl.java	11.11% <0.00%> (ø)
...in/java/azkaban/execapp/AzkabanExecutorServer.java	5.17% <0.00%> (ø)
...in/java/azkaban/webapp/metrics/WebMetricsImpl.java	0.00% <0.00%> (ø)
.../src/main/java/azkaban/project/ProjectManager.java	39.42% <100.00%> (+1.78%)	⬆️
.../java/azkaban/imagemgmt/models/ImageOwnership.java	54.05% <0.00%> (-36.86%)	⬇️
.../java/azkaban/imagemgmt/daos/ImageTypeDaoImpl.java	11.92% <0.00%> (-2.65%)	⬇️
... and 16 more

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