DOC: fix problem with part of code example cut off

Probably a bug in the ipython directive, but for now just fixing by putting it in seperate code blocks (only the first def() rendered)
TST/REG/BUG: Make PeriodIndex work with Series objects
Merge pull request #7712 from cpcloud/period-index-constructor

BUG: PeriodIndex constructor doesn't work with Series objects
SQL: suppress warning for BIGINT with sqlite and sqlalchemy<0.8.2 (GH7433)
DOC: docstring for PeriodIndex
Merge pull request #7721 from cpcloud/period-index-docstring

DOC: docstring for PeriodIndex
CI: remove sql from 3.3 build entirely
Merge pull request #7719 from jorisvandenbossche/sql-bigint-sqlite-warning

SQL: suppress warning for BIGINT with sqlite and sqlalchemy<0.8.2 (GH7433)
DOC: clean up 0.14.1 whatsnew file
Merge pull request #7714 from jorisvandenbossche/doc-release

DOC: clean up 0.14.1 whatsnew file
RLS: v0.14.1 final
DOC: add v0.15.0.txt to whatsnew.txt
DOC: 0.15.0 release notes updates
DOC: fix docstring of DatetimeIndex.delete
DOC: fix indentation in v0.14.1.txt
CLN: Simplify LinePlot flow