[quant][doc] Adding a table comparing eager and fx graph mode (#50413)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/50413
Test Plan:
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Imported from OSS
Reviewed By: vkuzo
Differential Revision: D25886960
fbshipit-source-id: b99178d3900eedec920dbff28ab956f97be2661a