Better display headers in adoc tables

[cols="h,m,s,e"]
|===
|Cell in column 1, row 1
|Cell in column 2, row 1
|Cell in column 3, row 1
|Cell in column 4, row 1

|Cell in column 1, row 2
|Cell in column 2, row 2
|Cell in column 3, row 2
|Cell in column 4, row 2
|===

renders