DOC: DataFrame.resample docs could be improved

[jreback]

http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.resample.html?highlight=dataframe%20resample#pandas.DataFrame.resample

These are the same docs for both Series & DataFrame. so might be nice to add some DataFrame examples (and use on / axis parameters). So may need to move these to a shared_docs template to suppport this.

[rishikksh20]

There is one more issue in this page where following link not formatted :
To learn more about the offset strings, please see ` this link
http://pandas.pydata.org/pandas-docs/stable/timeseries.html#offset-aliases`__.

I can take this issue. Please guide me little bit about docs and shared_docs template.

[jorisvandenbossche]

@jreback this might be closed by #15627. But there we choose to just add example for DataFrame in the existing docstring (so have a unified docstring for Series and DataFrame with examples for both).
But in principle we could also split off the examples and only add those relevant to Series or DataFrame (but not sure if I find this worth the complexity here).

[jreback]

in this case i think this is fine

resample is pretty much the same (meaning signature is the same), unlike say sort_values for Series/Dataframe