* update 2.0 public api in nn

* replace Chinese character cause error in ci;synchronization with pr:#32588 to avoid 'ascii' codec in python2

* numbers used in paddle.nn.functional.norm but not imported

* fix code bugs

* fix code bugs test=document_fix

* fix code bugs test=document_fix

* fix examples, test=document_fix

* fix, test=document_fix

As the title

* upgrade comment string to raw string

* fix string in

* fix string with ' '

* revert update on comments

* upgrade only necessary

* fix sample code checker

* fix comments with '''

* fix 2.0api, test=develop

* fix, test=develop

* add weight_norm, test=develop