Update images in README and spacing edits

[dqii]

No description provided.

[github-actions]

Benchmarks

metric	old	new	pct change
recall (after create)	0.740	0.740	-
recall (after insert)	0.766	0.782	+2.09%
select bulk tps	501.859	478.671	-4.62%
select bulk latency (ms)	15.662	15.736	+0.47%
select bulk latency (stddev ms)	2.143	4.270	+99.25%
create latency (ms)	1210.560	1217.179	+0.55%
insert bulk tps	11.276	10.719	-4.94%
insert bulk latency (ms)	88.653	93.285	+5.22%
insert bulk latency (stddev ms)	2.934	3.805	+29.69%
disk usage (bytes)	6348800.000	6348800.000	-

[codecov]

Codecov Report

Merging #225 (13b1193) into main (09c3dfe) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #225   +/-   ##
=======================================
  Coverage   77.65%   77.65%           
=======================================
  Files          22       22           
  Lines        1504     1504           
  Branches      383      383           
=======================================
  Hits         1168     1168           
  Misses        164      164           
  Partials      172      172