fix review comment from @TallTed

Author: michielbdejong

Documentation/conventions.md

@@ -20,7 +20,6 @@ For short-hand, we will use the following namespace prefixes here:
 * @prefix schema: <http://schema.org/>.
 * @prefix sioc: <http://rdfs.org/sioc/ns#>.
 * @prefix solid: <http://www.w3.org/ns/solid/terms#>.
-* @prefix sioc: <http://rdfs.org/sioc/ns#>.
 * @prefix stat <http://www.w3.org/ns/posix/stat#>.
 * @prefix ui: <http://www.w3.org/ns/ui#>.
 * @prefix vcard: <http://www.w3.org/2006/vcard/ns#>.
@@ -232,4 +231,4 @@ When you add a 'Folder' tool, the databrowser creates a new LDP container. As an
 * </foo/> ldp:contains </foo/bar.ttl>
 
 ## Source
-When you add a 'Source' tool to a container, it creates an empty document as an LDP resource. The content type will be guessed from the extension, for instance source.ttl will be a Turtle document, source.txt will be text/plain, etc.
+When you add a 'Source' tool to a container, it creates an empty document as an LDP resource. The content type will be guessed from the extension, for instance source.ttl will be a Turtle document, source.txt will be text/plain, etc.