Add example about atomic_op

[PierreZ]

No description provided.

[codecov-commenter]

Codecov Report

Merging #63 (d783844) into main (7a838a5) will increase coverage by 0.08%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main      #63      +/-   ##
==========================================
+ Coverage   83.52%   83.60%   +0.08%     
==========================================
  Files          24       24              
  Lines        4806     4820      +14     
==========================================
+ Hits         4014     4030      +16     
+ Misses        792      790       -2     

Impacted Files	Coverage Δ
foundationdb-bindingtester/src/main.rs	89.43% <0.00%> (-0.26%)	⬇️
foundationdb/src/tuple/subspace.rs	99.03% <0.00%> (+0.14%)	⬆️
foundationdb/src/directory/directory_layer.rs	93.30% <0.00%> (+1.21%)	⬆️

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[coveralls]

Pull Request Test Coverage Report for Build 2469413407

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 7 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.09%) to 75.324%

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Files with Coverage Reduction	New Missed Lines	%
foundationdb/src/directory/directory_layer.rs	3	93.31%
foundationdb-bindingtester/src/main.rs	4	89.43%

Totals
Change from base Build 2356888996:	0.09%
Covered Lines:	4185
Relevant Lines:	5556

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💛 - Coveralls