Update Symfony docs

[franmomu]

Based on what @DubbleClick did in https://github.com/doctrine-extensions/DoctrineExtensions/pull/2639/files#diff-531b03ac1e9de5d271d400acc8d449fa4f5a7d68d3a1469d3ac8c00119925c61

Better to have this in a separated PR, I think we can remove the reference to the Symfony version, doctrine event listeners will work in versions of symfony < 6.3, if there are differences between versions we can add a section in the same document.

I've updated a bit the code to add types and also use attribute mapping instead of annotation by default.

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (ef277c9) 79.22% compared to head (f14a612) 79.22%.
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2667   +/-   ##
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  Coverage   79.22%   79.22%           
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  Files         161      161           
  Lines        8415     8415           
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  Hits         6667     6667           
  Misses       1748     1748           

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[phansys]

Thank you @franmomu!