git.txt: remove redundant language

The documentation for GIT_ALLOW_PROTOCOL has a sentence that adds no
value, since it repeats the meaning from the previous sentence (twice!).

The word "whitelist" has cultural implications that are not inclusive,
which brought attention to this sentence.

Helped-by: Jeff King <peff@peff.net>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git.txt

@@ -885,9 +885,7 @@ for full details.
 	If set to a colon-separated list of protocols, behave as if
 	`protocol.allow` is set to `never`, and each of the listed
 	protocols has `protocol.<name>.allow` set to `always`
-	(overriding any existing configuration). In other words, any
-	protocol not mentioned will be disallowed (i.e., this is a
-	whitelist, not a blacklist). See the description of
+	(overriding any existing configuration). See the description of
 	`protocol.allow` in linkgit:git-config[1] for more details.
 
 `GIT_PROTOCOL_FROM_USER`::