Fixed small error of the phrase "parser" being duplicated.

Signed-off-by: Zsolt Gyulai (zgyulai) <zsolt.gyulai@quest.com>

Author: zsoltgyulai94

_includes/doc/admin-guide/default-prefix.md

@@ -1,8 +1,8 @@
-By default, {{ page.parser }}-parser() uses the .{{ page.prefix | default: page.parser }}. prefix. To modify it, use
+By default, {{ page.parser }}() uses the .{{ page.prefix | default: page.parser }}. prefix. To modify it, use
 the following format:
 
 ```config
 parser {
-    {{page.parser}}-parser(prefix("myprefix."));
+    {{page.parser}}(prefix("myprefix."));
 };
 ```