Doc updates for indexers. change word size max from 25 to 50 phrase search syntax updated clear up wording for automatic selection of xapian/whoosh link user_guide to admin_guide for finding syntax for native_fts searches.

#!/usr/bin/env python
from __future__ import print_function
import zlib, base64, sys
print(base64.encodestring(zlib.compress(sys.stdin.read())))