BUG: offset normalize option may not work in addition/subtraction
Merge pull request #7705 from sinhrks/normalize_bug

BUG: offset normalize option may not work in addition/subtraction
DOC: fix doc build warnings

- indentation error in the option docstring
- link to options page that has moved
- select_dtypes docstring
TST: additional network error catching (test_html/test_spam_html)
Merge pull request #7713 from jorisvandenbossche/doc-fixes3

DOC: fix doc build warnings
BUG: offsets.apply doesnt preserve nanosecond