Add datetimeindex accessors to timeseries documentation (timeseries.rst)
All of the timestamp/datetimeindex accessors are not in the timeseries documentation (they currently are only referenced in the api documentation). It would be great to have a section on these accessors:

.year  
.month
.day  
.hour  
.minute 
.second 
.microsecond  
.nanosecond 
.date
.time
.dayofyear  
.weekofyear 
.week  
.dayofweek
.weekday
.quarter  
.is_month_start
.is_month_end
.is_quarter_start
.is_quarter_end
.is_year_start
.is_year_end

Additionally, some of these accessors (e.g. weekofyear) are not frequency aware and users should be alerted to that fact. 
