Hi Team,
We are using the ES version as 7.3.2 for our environment.
Now we are planning to upgrade our elasticsearch to 7.17.3.
May i know is there any search speed or indexing speed will increase after upgrade?
Hi @Siva_Karan
There are many many enhancements (to numerous to list) from 7.3 to 7.17 so I would expect some improvements BUT the only way to be sure is to test! 
Also, you should upgrade to the latest 7.17.15.
Is there any documentation for enhancements
You would probably need to go though the release notes for each release. The release you are using is over 4 years old and has been EOL for a long time, so the release notes will cover a good amount of development.