Update Additional-Reading.md

[mbialorucki]

Check existing links, add new links about RxAndroid #6132

[akarnokd]

Could you please mark entries that contain only 1.x code with **(1.x)** and mixed ones with **(1.x & 2.x)**?

[mbialorucki]

Done

[codecov]

Codecov Report

Merging #6180 into 2.x will increase coverage by 0.04%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##               2.x    #6180      +/-   ##
===========================================
+ Coverage     98.2%   98.25%   +0.04%     
- Complexity    6196     6200       +4     
===========================================
  Files          667      667              
  Lines        44880    44880              
  Branches      6214     6214              
===========================================
+ Hits         44073    44095      +22     
+ Misses         261      249      -12     
+ Partials       546      536      -10

Impacted Files	Coverage Δ	Complexity Δ
...nternal/operators/observable/ObservableCreate.java	95.72% <0%> (-3.42%)	2% <0%> (ø)
...ernal/operators/flowable/FlowableFlatMapMaybe.java	90.82% <0%> (-2.42%)	2% <0%> (ø)
.../internal/disposables/ListCompositeDisposable.java	98% <0%> (-2%)	34% <0%> (-1%)
...x/internal/operators/flowable/FlowablePublish.java	97.87% <0%> (-1.71%)	11% <0%> (ø)
...ternal/operators/completable/CompletableMerge.java	96.42% <0%> (-1.2%)	2% <0%> (ø)
...rnal/operators/observable/ObservableSwitchMap.java	95.21% <0%> (-1.07%)	3% <0%> (ø)
...perators/observable/ObservableMergeWithSingle.java	99.06% <0%> (-0.94%)	2% <0%> (ø)
...ava/io/reactivex/processors/BehaviorProcessor.java	98.2% <0%> (-0.9%)	59% <0%> (-1%)
...operators/observable/ObservableMergeWithMaybe.java	99.1% <0%> (-0.9%)	2% <0%> (ø)
...x/internal/operators/flowable/FlowableGroupBy.java	94.95% <0%> (-0.57%)	3% <0%> (ø)
... and 18 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 e2a2159...8db2904. Read the comment docs.