* test=document_preview
Fix the op API of diag, greater_equal, greater_than, less_equal, linspace, not_equal, rank, reduce_all, reduce_any, rsqrt, sign, unique_with_counts, where, zeros_like.

* test=document_preview
Fix some problems in fisrt commit, main format problem.

* test=document_preview
Fix document, the return type of greater_equal, greater_than, less_equal, not_equal.

* test=document_preview
Fix the format in doc of op rsqrt.