[CARBONDATA-3791] update pycarbon document
[CARBONDATA-3791] update pycarbon document

Why is this PR needed?
setup.cfg lies outside the folder. so need to update the document on the same.

What changes were proposed in this PR?
setup.cfg lies outside the folder. so need to update the document on the same.
some other minor fix.

This closes #3767

zzcclp/carbondata,zzcclp/carbondata,zzcclp/carbondata,zzcclp/carbondata,zzcclp/carbondata