chore: update inventory detail docs, handle system not found more nicely

[mkholjuraev]

Updates inventory detail docs, and hides the main section if the system does not exist.

To test the main section related change:

1. Open one of the oldest systems (we need to choose a system that is not needed)
2. Click on the Delete button on the top right side.
3. Refresh the page. You should see the old nicely designed system not found component.

[adonispuente]

PR works as intended. Observed no issues when testing against other apps as well

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: -0.98 ⚠️

Comparison is base (6b42a24) 68.60% compared to head (8fb6cee) 67.63%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1774      +/-   ##
==========================================
- Coverage   68.60%   67.63%   -0.98%     
==========================================
  Files         124      124              
  Lines        2762     2762              
  Branches      915      915              
==========================================
- Hits         1895     1868      -27     
- Misses        867      894      +27     

Impacted Files	Coverage Δ
src/components/InventoryDetail/InventoryDetail.js	0.00% <0.00%> (ø)
src/routes/InventoryDetail.js	0.00% <ø> (ø)
src/api/api.js	45.78% <0.00%> (-18.08%)	⬇️
src/routes/InventoryTable.js	60.34% <0.00%> (-7.76%)	⬇️
src/components/InventoryTable/InventoryTable.js	94.73% <0.00%> (-5.27%)	⬇️

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[gkarat]

🎉 This PR is included in version 1.7.2 🎉

The release is available on GitHub release

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