document the implicit mapping for text/gemini

and remove the explicit mapping from the documentation and test files.

gmid.conf.5

@@ -532,7 +532,7 @@ By default
 .Nm gmid
 uses the following mapping if no
 .Ic types
-block is used:
+block is defined:
 .Bl -tag -offset indent -width 15m -compact
 .It application/pdf
 pdf
@@ -553,6 +553,16 @@ diff patch
 .It text/xml
 xml
 .El
+.Pp
+As an exception,
+.Nm gmid
+uses the MIME type
+.Ar text/gemini
+for file extensions
+.Ar gemini
+or
+.Ar gmi
+if no mapping was found.
 .Sh EXAMPLES
 The following is an example of a possible configuration for a site
 that enables only TLSv1.3, adds the MIME types mapping from
@@ -564,8 +574,6 @@ ipv6 on		# enable ipv6
 protocols "tlsv1.3"
 
 types {
-	text/gemini	gemini gmi
-
 	include "/usr/share/misc/mime.types"
 }
 

regress/example.mime.types

@@ -7,7 +7,3 @@ application/x-perl			pl pm
 
 text/x-mandoc				1 2 3 4 5 6 7 8 9
 text/x-mandoc				3bsd
-
-# this needs to be present because `types' overrides
-# the built-in list.
-text/gemini				gemini gmi

site/faq.gmi

@@ -13,8 +13,6 @@ gmid, like many other servers, uses a list of known file extensions to decide wh
 
 ``` example of how to use the type rule in the configuration file
 types {
-	text/gemini		gemini gmi
-
 	application/postscript	ps eps ai
 	application/rss+xml	rss