Improve tooltip for the "WITHOUT ROWID" checkbox

[vlakoff]

Notably, the required PRIMARY KEY can be of any type, and can be composite.

Refs:

• Clustered Indexes and the WITHOUT ROWID Optimization - in particular in section 4:

  The WITHOUT ROWID optimization is likely to be helpful for tables that have non-integer or composite (multi-column) PRIMARY KEYs and that do not store large strings or BLOBs.

• SQLite Autoincrement - in particular at the end of the page:

  Because AUTOINCREMENT keyword changes the behavior of the ROWID selection algorithm, AUTOINCREMENT is not allowed on WITHOUT ROWID tables or on any table column other than INTEGER PRIMARY KEY. Any attempt to use AUTOINCREMENT on a WITHOUT ROWID table or on a column other than the INTEGER PRIMARY KEY column results in an error.

Not sure how the translations should be handled. Does "lupdate" handle everything? (updating the <source> tags, and marking the <translations> tags as needing update)