[docs] Advise about celery 4.3.0 requirement on redis

[dpgaspar]

CATEGORY

• Bug Fix
• Enhancement (new features, refinement)
• Refactor
• Add tests
• Build / Development Environment
• Documentation

SUMMARY

UPDATING doc warns about celery version bump to 4.3.0 and new requirement for redis > 3.2.
Follows PR #7848

ADDITIONAL INFORMATION

• Has associated issue:
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

REVIEWERS

[codecov-io]

Codecov Report

Merging #7872 into master will decrease coverage by 8.18%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #7872      +/-   ##
==========================================
- Coverage   73.96%   65.77%   -8.19%     
==========================================
  Files         107      461     +354     
  Lines       11551    22103   +10552     
  Branches        0     2423    +2423     
==========================================
+ Hits         8544    14539    +5995     
- Misses       3007     7443    +4436     
- Partials        0      121     +121

Impacted Files	Coverage Δ
superset/assets/src/components/Checkbox.jsx	100% <0%> (ø)
...ations/deckgl/layers/Polygon/PolygonChartPlugin.js	0% <0%> (ø)
...ets/src/dashboard/components/dnd/DragDroppable.jsx	94.59% <0%> (ø)
...c/visualizations/deckgl/layers/Polygon/Polygon.jsx	0% <0%> (ø)
superset/assets/src/components/EditableTitle.jsx	81.53% <0%> (ø)
superset/assets/src/setup/setupPlugins.js	0% <0%> (ø)
...t/assets/src/components/InfoTooltipWithTrigger.jsx	41.66% <0%> (ø)
.../src/dashboard/components/UndoRedoKeylisteners.jsx	9.52% <0%> (ø)
...ts/src/explore/components/ExploreActionButtons.jsx	100% <0%> (ø)
...ssets/src/visualizations/deckgl/layers/Hex/Hex.jsx	0% <0%> (ø)
... and 344 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 eed99b1...e870654. Read the comment docs.

[codecov-io]

Codecov Report

Merging #7872 into master will decrease coverage by 8.18%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #7872      +/-   ##
==========================================
- Coverage   73.96%   65.77%   -8.19%     
==========================================
  Files         107      461     +354     
  Lines       11551    22103   +10552     
  Branches        0     2423    +2423     
==========================================
+ Hits         8544    14539    +5995     
- Misses       3007     7443    +4436     
- Partials        0      121     +121

Impacted Files	Coverage Δ
superset/assets/src/components/Checkbox.jsx	100% <0%> (ø)
...ations/deckgl/layers/Polygon/PolygonChartPlugin.js	0% <0%> (ø)
...ets/src/dashboard/components/dnd/DragDroppable.jsx	94.59% <0%> (ø)
...c/visualizations/deckgl/layers/Polygon/Polygon.jsx	0% <0%> (ø)
superset/assets/src/components/EditableTitle.jsx	81.53% <0%> (ø)
superset/assets/src/setup/setupPlugins.js	0% <0%> (ø)
...t/assets/src/components/InfoTooltipWithTrigger.jsx	41.66% <0%> (ø)
.../src/dashboard/components/UndoRedoKeylisteners.jsx	9.52% <0%> (ø)
...ts/src/explore/components/ExploreActionButtons.jsx	100% <0%> (ø)
...ssets/src/visualizations/deckgl/layers/Hex/Hex.jsx	0% <0%> (ø)
... and 344 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 eed99b1...e870654. Read the comment docs.