Add Publication_Channel.md and relationship between document and publ…

…ication channel (#26)

entities/Document.md

@@ -29,6 +29,8 @@ publication date: [Date](../datatypes/Date.md) in case the document has gone thr
 
 <a name="rel__provides-evidence-of">provides-evidence-of</a> / [is-evidenced-by](../entities/Expertise_and_Skills_Possession.md#user-content-rel__is-evidenced-by) : A Document can provide evidence of any number of [Expertise and Skills Possessions](../entities/Expertise_and_Skills_Possession.md).
 
+<a name="rel__published-via-channel">published-via-channel</a> / [has-publication](../entities/Publication_Channel.md#user-content-rel__has-publication) : A Document can be published via [publication channel](../entities/Publication_Channel.md).
+
 ---
 ## Matches
 1. Close match of [Bibo Document](http://purl.org/ontology/bibo/Document)

entities/Publication_Channel.md

@@ -0,0 +1,19 @@
+# Publication Channel
+
+## Definition
+A Publication Channel is a medium for publishing documents. 
+
+## Usage notes
+An example of publication channel is a publication series such as journal or book series (e.g. Lecture Notes in Computer Sciences). Moreover, a repository is also a publication channel. 
+
+## Attributes
+
+## Relationships
+
+<a name="rel__has-publication">has-publication</a> / [published-via-channel](../entities/Document.md#user-content-rel__published-via-channel) : A Publication Channel has any number of [documents](../entities/Document.md) which has been published via the channel.
+
+---
+## Matches
+
+## References
+