Add help for meson rewrite to the man page.

The added help text was derived from the output of the meson help
command much like the markdown online help is derived.

man/meson.1

@@ -406,6 +406,53 @@ Remove all wrap-based subproject artifacts
 \fBpackagefiles\fR
 Manage the packagefiles overlay
 
+.SH The rewrite command
+
+.B meson rewrite
+modifies the project definition.
+ 
+.B meson rewrite [
+.I options
+.B ] [
+.I command
+.B ]
+
+.SS "options:"
+
+.TP
+\fB\-h, \-\-help\fR
+show this help message and exit
+
+.TP
+\fB\-s SRCDIR, \-\-sourcedir SRCDIR\fR
+Path to source directory.
+
+.TP
+\fB\-V, \-\-verbose\fR
+Enable verbose output
+
+.TP
+\fB\-S, \-\-skip\-errors\fR
+Skip errors instead of aborting
+
+.SS "commands:"
+
+.TP
+\fBtarget (tgt)\fR
+Modify a target
+
+.TP
+\fBkwargs\fR
+Modify keyword arguments
+
+.TP
+\fBdefault-options (def)\fR
+Modify the project default options
+
+.TP
+\fBcommand (cmd)\fR
+Execute a JSON array of commands
+
 .SH EXIT STATUS
 
 .TP