[Matlab] Add basic NamedEntity documentation

Author: mpsonntag

+nix/NamedEntity.m

@@ -1,3 +1,26 @@
+% MixIn class for NIX entites with basic dynamic properties.
+%
+% In addition to the properties defined by nix.Entity most entities of the NIX data model
+% further provide the properties id, name, type and definition.
+%
+% The id property of an entity is automatically assigned and serves as a machine readable 
+% unique identifier. The name property of an entity serves as a human readable identifier 
+% and can be set at the creation of an entity. The type property is used to allow the 
+% specification of additional semantic meaning for an entity and therefore can introduce 
+% domain-specificity into the generic data model. The optional definition property allows 
+% the user to add a freely assignable textual definition to the entity.
+%
+% Dynamic properties:
+%   id (char):          read-only, automatically created id of the entity.
+%   name (char):        read-only, name of the entity.      
+%   type (char):        read-write, type can be used to give semantic meaning to an 
+%                         entity and expose it to search methods in a broader context.
+%   definition (char):  read-write, additional description of the entity.
+%
+% See also: nix.Block, nix.Group, nix.DataArray, nix.Source, nix.Tag,
+% nix.MultiTag, nix.Section.
+%
+%
 % Copyright (c) 2016, German Neuroinformatics Node (G-Node)
 %
 % All rights reserved.
@@ -7,8 +30,6 @@
 % LICENSE file in the root of the Project.
 
 classdef NamedEntity < nix.Entity
-    % NamedEntity
-    % base class for nix entities with name/type/definition
 
     methods
         function obj = NamedEntity(h)
@@ -22,8 +43,16 @@
         end
 
         function r = compare(obj, entity)
-        % Compares first name and second id, return > 0 if the entity 
-        % is larger than the other, 0 if both are equal, and < 0 otherwise.
+            % Checks two NIX entities of the same class for equality.
+            %
+            % The name property is the first comparison. If they are the same, 
+            % the ids of the entities will be compared.
+            %
+            % Returns:  (double)  0 if both entities are equal.
+            %                     > or < 0 if the entities are different.
+            %
+            % Example:  check = currSource.compare(otherSource);
+
             if (~isa(obj, class(entity)))
                 err.identifier = 'NIXMX:InvalidArgument';
                 err.message = 'Only entities of the same class can be compared.';