fix: getExchangeRxns correct 'out' flag definition (#589)

Author: edkerk

core/getExchangeRxns.m

@@ -26,8 +26,8 @@
 %                                 positive flux value would imply uptake,
 %                                 but reaction bounds are not considered
 %                       'out'     reactions where the boundary metabolite
-%                                 is the substrate of the reaction, a
-%                                 positive flux value would imply uptake,
+%                                 is the product of the reaction, a
+%                                 negative flux value would imply uptake,
 %                                 but reaction bounds are not considered.
 %
 % Output:

doc/core/getExchangeRxns.html

@@ -54,8 +54,8 @@ <h2><a name="_description"></a>DESCRIPTION <a href="#_top"><img alt="^" border="
                                  positive flux value would imply uptake,
                                  but reaction bounds are not considered
                        'out'     reactions where the boundary metabolite
-                                 is the substrate of the reaction, a
-                                 positive flux value would imply uptake,
+                                 is the product of the reaction, a
+                                 negative flux value would imply uptake,
                                  but reaction bounds are not considered.
 
  Output:
@@ -109,8 +109,8 @@ <h2><a name="_source"></a>SOURCE CODE <a href="#_top"><img alt="^" border="0" sr
 0026 <span class="comment">%                                 positive flux value would imply uptake,</span>
 0027 <span class="comment">%                                 but reaction bounds are not considered</span>
 0028 <span class="comment">%                       'out'     reactions where the boundary metabolite</span>
-0029 <span class="comment">%                                 is the substrate of the reaction, a</span>
-0030 <span class="comment">%                                 positive flux value would imply uptake,</span>
+0029 <span class="comment">%                                 is the product of the reaction, a</span>
+0030 <span class="comment">%                                 negative flux value would imply uptake,</span>
 0031 <span class="comment">%                                 but reaction bounds are not considered.</span>
 0032 <span class="comment">%</span>
 0033 <span class="comment">% Output:</span>