Add integer range search example

[petr-tik]

Copied and simplified the example from the range_query mod

Related to #372

[codecov]

Codecov Report

Merging #490 into master will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #490      +/-   ##
==========================================
+ Coverage      91%   91.02%   +0.01%     
==========================================
  Files         164      164              
  Lines       15293    15293              
==========================================
+ Hits        13918    13921       +3     
+ Misses       1375     1372       -3

Impacted Files	Coverage Δ
src/collector/top_collector.rs	95.45% <0%> (-1.14%)	⬇️
src/collector/top_score_collector.rs	100% <0%> (+1.53%)	⬆️
src/store/writer.rs	98.11% <0%> (+5.66%)	⬆️

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[fulmicoton]

thx