luci-base: fix docs for TableSection

There are repeated values (TableSection inherits identically named
values from TypedSection which do not make sense to recreate).

There seemed to be other errors. E.g. TypedSection for FlagValue
properties, which mean that TypedSection got tooltip + tooltipicon,
and by virtue of the above error, GridSection inherited this too.

Signed-off-by: Paul Donald <newtwen@gmail.com>