Update documentation on URI#join and URI#/ to clarify how arguments are treated.

Fixes #371.

Author: gkellogg

lib/rdf/model/uri.rb

@@ -407,7 +407,7 @@ def canonicalize!
     # @see <http://tools.ietf.org/html/rfc3986#section-5.2>
     # @see RDF::URI#/
     # @see RDF::URI#+
-    # @param  [Array<String, RDF::URI, #to_s>] uris
+    # @param  [Array<String, RDF::URI, #to_s>] uris absolute or relative URIs.
     # @return [RDF::URI]
     # @see http://tools.ietf.org/html/rfc3986#section-5.2.2
     # @see http://tools.ietf.org/html/rfc3986#section-5.2.3
@@ -458,6 +458,8 @@ def join(*uris)
     # this method does not perform any normalization, removal of spurious
     # paths, or removal of parent directory references `(/../)`.
     #
+    # When `fragment` is a path segment containing a colon, best practice is to prepend a `./` and use {#join}, which resolves dot-segments.
+    #
     # See also `#+`, which concatenates the string forms of two URIs without
     # any sort of checking or processing.
     #