docs: docstrings for drivers

[cristianmtr]

No description provided.

[codecov]

Codecov Report

Merging #1951 (466bfeb) into master (d153381) will decrease coverage by 0.88%.
The diff coverage is 83.33%.

@@            Coverage Diff             @@
##           master    #1951      +/-   ##
==========================================
- Coverage   86.52%   85.63%   -0.89%     
==========================================
  Files         148      148              
  Lines        7093     7093              
==========================================
- Hits         6137     6074      -63     
- Misses        956     1019      +63     

Impacted Files	Coverage Δ
jina/drivers/convertdriver.py	93.93% <ø> (ø)
jina/drivers/encode.py	91.30% <ø> (-2.90%)	⬇️
jina/drivers/evaluate.py	98.27% <ø> (ø)
jina/drivers/querylang/select.py	72.41% <ø> (-17.25%)	⬇️
jina/drivers/predict.py	38.88% <50.00%> (-53.71%)	⬇️
jina/drivers/control.py	95.08% <100.00%> (ø)
jina/drivers/reduce.py	75.60% <0.00%> (-24.40%)	⬇️
jina/drivers/querylang/reverse.py	77.77% <0.00%> (-22.23%)	⬇️
... and 7 more

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[github-actions]

Latency summary

Current PR yields:

• 😶 index QPS at 1056, delta to last 3 avg.: +0%
• 🐢🐢 query QPS at 17, delta to last 3 avg.: -7%

Breakdown

Version	Index QPS	Query QPS
current	1056	17
1.0.1	1069	17
1.0.0	1046	19

Backed by latency-tracking. Further commits will update this comment.

[nan-wang]

LGTM👍