Change from ‘text/plain’ to ‘text/troff’ for the MIME
content-type for troff files per RFC 4263.

Might this break other things? /sys/lib/mimetype uses
something completely different.
—btdn

Reference: /n/sources/patch/applied/file-text.troff
Date: Fri Jan 19 00:34:43 CET 2007
Signed-off-by: newmanbe@sdf.lonestar.org

--- /sys/src/cmd/file.c	Wed Jan 17 00:28:35 2007
+++ /sys/src/cmd/file.c	Wed Jan 17 00:43:20 2007
@@ -790,18 +790,18 @@
 	"P3\n",			"ppm",				3,	"image/ppm",
 	"P6\n",			"ppm",				3,	"image/ppm",
 	"/* XPM */\n",	"xbm",				10,	"image/xbm",
-	".HTML ",		"troff -ms input",	6,	"text/plain",
-	".LP",			"troff -ms input",	3,	"text/plain",
-	".ND",			"troff -ms input",	3,	"text/plain",
-	".PP",			"troff -ms input",	3,	"text/plain",
-	".TL",			"troff -ms input",	3,	"text/plain",
-	".TR",			"troff -ms input",	3,	"text/plain",
-	".TH",			"manual page",		3,	"text/plain",
-	".\\\"",		"troff input",		3,	"text/plain",
-	".de",			"troff input",		3,	"text/plain",
-	".if",			"troff input",		3,	"text/plain",
-	".nr",			"troff input",		3,	"text/plain",
-	".tr",			"troff input",		3,	"text/plain",
+	".HTML ",		"troff -ms input",	6,	"text/troff",
+	".LP",			"troff -ms input",	3,	"text/troff",
+	".ND",			"troff -ms input",	3,	"text/troff",
+	".PP",			"troff -ms input",	3,	"text/troff",
+	".TL",			"troff -ms input",	3,	"text/troff",
+	".TR",			"troff -ms input",	3,	"text/troff",
+	".TH",			"manual page",		3,	"text/troff",
+	".\\\"",		"troff input",		3,	"text/troff",
+	".de",			"troff input",		3,	"text/troff",
+	".if",			"troff input",		3,	"text/troff",
+	".nr",			"troff input",		3,	"text/troff",
+	".tr",			"troff input",		3,	"text/troff",
 	"vac:",			"venti score",		4,	"text/plain",
 	0,0,0,0
 };