Docs clarification for some reblocking-related funkiness

[ldgauthier]

No description provided.

[codecov]

Codecov Report

Merging #7846 (7a30ea4) into master (a3141f7) will decrease coverage by 0.006%.
The diff coverage is n/a.

@@               Coverage Diff               @@
##              master     #7846       +/-   ##
===============================================
- Coverage     86.955%   86.948%   -0.006%     
- Complexity     36920     36927        +7     
===============================================
  Files           2218      2219        +1     
  Lines         173663    173673       +10     
  Branches       18751     18755        +4     
===============================================
- Hits          151008    151006        -2     
- Misses         16049     16055        +6     
- Partials        6606      6612        +6     

Impacted Files	Coverage Δ
.../hellbender/tools/walkers/GenotypeGVCFsEngine.java	90.826% <ø> (ø)
...tools/walkers/haplotypecaller/HaplotypeCaller.java	85.714% <0.000%> (-6.286%)	⬇️
...notyper/GenotypeCalculationArgumentCollection.java	89.474% <0.000%> (ø)
...otypecaller/HaplotypeCallerArgumentCollection.java	100.000% <0.000%> (ø)
...typecaller/LikelihoodEngineArgumentCollection.java	100.000% <0.000%> (ø)
...ecaller/AssemblyBasedCallerArgumentCollection.java	100.000% <0.000%> (ø)
...nstitute/hellbender/cmdline/ModeArgumentUtils.java	69.231% <0.000%> (ø)
...tute/hellbender/engine/AssemblyRegionIterator.java	92.784% <0.000%> (+0.152%)	⬆️

[ldgauthier]

@droazen I'm not thrilled that adding Javadoc decreased our coverage, but we've gone for years without code coverage, so I can just ignore this.