Correct an mdoc error; add a sentence about tar's ancestors "tp" and "tap."

lib/libarchive/tar.5

@@ -396,7 +396,7 @@ The full minor and major numbers for device nodes.
 The device number, inode number, and link count for the entry.
 In particular, note that a pax interchange format archive using Joerg
 Schilling's
-Cm SCHILY.*
+.Cm SCHILY.*
 extensions can store all of the data from
 .Va struct stat .
 .It Cm VENDOR.*
@@ -689,6 +689,11 @@ The pax interchange file format is new with
 A
 .Nm tar
 command appeared in Seventh Edition Unix, which was released in January, 1979.
+It replaced the
+.Nm tp
+program from Fourth Edition Unix which in turn replaced the
+.Nm tap
+program from First Edition Unix.
 John Gilmore's
 .Nm pdtar
 public-domain implementation (circa 1987) was highly influential