DOC: Update docs to reflect 5y default

Author: addisonlynch

docs/source/whatsnew/v0.8.0.txt

@@ -31,7 +31,7 @@ Enhancements
 - Added testing on Python 3.7 (:issue:`667`)
 - Allow IEX to read less than 1 year of data (:issue:`649`)
 - Allow data download from Poland using stooq (:issue:`597`)
-- All time series readers now use a rolling default starting date (most are 15 years before the current date. Intraday readers are 3-5 days from the current date)
+- All time series readers now use a rolling default starting date (most are 5 years before the current date. Intraday readers are 3-5 days from the current date)
 
 .. _whatsnew_080.api_breaking:
 
@@ -64,7 +64,6 @@ Bug Fixes
 - Adjust Alphavantage time series reader to account for descending ordering. (:issue:`666`)
 - Fix bug in downloading index historical constituents. (:issue:`591`)
 - Fix a bug that occurs when an endpoint returns has no data for a date range. (:issue:`640`)
-- Fix a bug that caused an exception to be raised when IEX default dates are used (:issue:`607`)
 
 Contributors
 ~~~~~~~~~~~~

pandas_datareader/yahoo/daily.py

@@ -25,7 +25,7 @@ class YahooDailyReader(_DailyBaseReader):
     start : string, int, date, datetime, timestamp
         Starting date. Parses many different kind of date
         representations (e.g., 'JAN-01-2010', '1/1/10', 'Jan, 1, 1980'). Defaults to
-        15 years before current date.
+        5 years before current date.
     end : string, int, date, datetime, timestamp
         Ending date
     retry_count : int, default 3