Minor changes in the quickstart guide for installation of bdb-driver

[muawiakh]

• Adding python development library and headers as a dependency for cryptography.
• Also reference to official cryptography installation guide.
• Restructure document

[codecov-io]

Codecov Report

Merging #325 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #325   +/-   ##
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  Coverage   99.15%   99.15%           
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  Files           9        9           
  Lines         236      236           
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  Hits          234      234           
  Misses          2        2