doc: diff-options.adoc: make *.noprefix split translatable

We cannot split single words like what we did in the previous
commit. That is because the doc translations are processed in
bigger chunks.

Instead write the two paragraphs with the only variations being this
configuration variable.

Reported-by: Jean-Noël Avila <jn.avila@free.fr>
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: LemmingAvalanche

Documentation/diff-options.adoc

@@ -859,12 +859,18 @@ endif::git-format-patch[]
 	Do not show any source or destination prefix.
 
 `--default-prefix`::
+ifdef::git-format-patch[]
 	Use the default source and destination prefixes ("a/" and "b/").
-	This overrides configuration variables such as
-ifndef::git-format-patch[`diff.noprefix`,]
-ifdef::git-format-patch[`format.noprefix`,]
+	This overrides configuration variables such as `format.noprefix`,
 	`diff.srcPrefix`, `diff.dstPrefix`, and `diff.mnemonicPrefix`
 	(see linkgit:git-config[1]).
+endif::git-format-patch[]
+ifndef::git-format-patch[]
+	Use the default source and destination prefixes ("a/" and "b/").
+	This overrides configuration variables such as `diff.noprefix`,
+	`diff.srcPrefix`, `diff.dstPrefix`, and `diff.mnemonicPrefix`
+	(see linkgit:git-config[1]).
+endif::git-format-patch[]
 
 `--line-prefix=<prefix>`::
 	Prepend an additional _<prefix>_ to every line of output.