8175786: Fix small doc issues
Reviewed-by: jjg, jlahoda

8173944: Reference Origin.MANDATED in getEnclosedElements specs
Reviewed-by: jlahoda

8173676: Improvements to javax.annotation.processing and javax.lang.model doc
Reviewed-by: anazarov

8173164: Resolve remaining HTML5 issues in javax.lang.model.*
Reviewed-by: martin

8054834: Modular Source Code
Reviewed-by: alanb, chegar, ihse, mduigou
Contributed-by: alan.bateman@oracle.com, alex.buckley@oracle.com, chris.hegarty@oracle.com, erik.joelsson@oracle.com, jonathan.gibbons@oracle.com, karen.kinnear@oracle.com, magnus.ihse.bursie@oracle.com, mandy.chung@oracle.com, mark.reinhold@oracle.com, paul.sandoz@oracle.com