Add explicit link to documentation page

[Andrea D'Amore]

Please add an explicit link to sqlite dialect documentation page in metadata documentation page, I was mislead by

See the SQLite dialect documentation for information on SQLite’s AUTOINCREMENT.

and went checking www.sqlite.org/autoinc.html instead

[Mike Bayer]

• add link to dialect docs for SQLite autoincrement from column autoincrement, fixes #3110

→ <<cset 3e4286079c76>>

[Mike Bayer]

• add link to dialect docs for SQLite autoincrement from column autoincrement, fixes #3110

→ <<cset 4b904621f6eb>>