Add manpage entry for _appcast_checkpoint.

Library/Homebrew/cask/lib/hbc/cli/internal_appcast_checkpoint.rb

@@ -50,7 +50,7 @@ module Hbc
       end
 
       def self.help
-        "prints (no flag) or calculates ('--calculate') a given Cask's (or URL's) appcast checkpoint"
+        "prints or calculates a given Cask's or URL's appcast checkpoint"
       end
 
       def self.needs_init?

Library/Homebrew/manpages/brew-cask.1.md

@@ -120,6 +120,13 @@ names, and other aspects of this manual are still subject to change.
 
     **`zap` may remove files which are shared between applications.**
 
+## INTERNAL COMMANDS
+
+  * `_appcast_checkpoint` [--calculate] [ <token> ... | <URL> ... ]:
+    Given a `token`, returns the current appcast checkpoint, or calculates
+    the appcast checkpoint if the `--calculate` flag is specified.  
+    Given a `URL`, calculates the appcast checkpoint for it.
+
 ## OPTIONS
 
 To make these options persistent, see the ENVIRONMENT section, below.

manpages/brew-cask.1

@@ -105,6 +105,15 @@ If the Cask definition contains a \fBzap\fR stanza, performs additional \fBzap\f
 .
 .IP "" 0
 .
+.SH "INTERNAL COMMANDS"
+.
+.TP
+\fB_appcast_checkpoint\fR [\-\-calculate] [ \fItoken\fR \.\.\. | \fIURL\fR \.\.\. ]
+Given a \fBtoken\fR, returns the current appcast checkpoint, or calculates the appcast checkpoint if the \fB\-\-calculate\fR flag is specified\.
+.
+.br
+Given a \fBURL\fR, calculates the appcast checkpoint for it\.
+.
 .SH "OPTIONS"
 To make these options persistent, see the ENVIRONMENT section, below\.
 .