clarify individual isolation level section
clarify individual isolation level section

also rewrite the "individual sessions" section
to not rely upon context from the previous section,
this is a bad habit and should be fixed whereever we can
find it becuase people click on individual sections out of
context.

Change-Id: I288ffcc84ff462fb36cd7f4075f39d53c55fbf35

j5int/sqlalchemy,zzzeek/sqlalchemy,j5int/sqlalchemy,sqlalchemy/sqlalchemy,monetate/sqlalchemy,monetate/sqlalchemy