cache support (-c option)

"Optionally the -c cachefile option can be used to cache the entries of
the log page up to the point of the last commit. The cachefile will store
the last commit id and the entries in the HTML table."

this caches the diffstat and commits, it is an expensive operation (twss).

stagit.1

@@ -1,4 +1,4 @@
-.Dd December 26, 2015
+.Dd May 1, 2016
 .Dt STAGIT 1
 .Os
 .Sh NAME
@@ -6,12 +6,26 @@
 .Nd static git page generator
 .Sh SYNOPSIS
 .Nm
-.Op Ar repodir
+.Op Fl c Ar cachefile
+.Ar repodir
 .Sh DESCRIPTION
 .Nm
 writes HTML pages for the repository
 .Ar repodir
-to the current directory. The following files will be written:
+to the current directory.
+.Pp
+Optionally the
+.Fl c Ar cachefile
+option can be used to cache the entries of the log page up to the point of
+the last commit. The
+.Ar cachefile
+will store the last commit id and the entries in the HTML table. It is up
+to the user to make sure the state of the
+.Ar cachefile
+is in sync with the history of the repository, for example a
+git push \-\-force can screw this up.
+.Pp
+The following files will be written:
 .Bl -tag -width Ds
 .It atom.xml
 Atom XML feed