message: add note on unsequenced regions to help boxes
diff: @@ -11,7 +11,7 @@ Line markers on sequence views represent mutations colored by the resulting nucl
  <HelpTipsColumnSeqViewLegend />
  -
  +Unsequenced regions at the 5' and 3' end are indicated as light gray shading.
  For a mapping between positions in the sequence, genes and clade-defining mutations, see Genome Annotation view below the table.
  Note that sometimes mutations are so close to each other that they overlap.
  