source node is not optional

Author: IoannisPanagiotas

doc/modules/ROOT/partials/algorithms/spanning-tree/specific-configuration.adoc

@@ -1,3 +1,3 @@
-| sourceNode                                                                      | Integer | null      | n/a        | The starting source node ID.
+| sourceNode                                                                      | Integer | n/a      | no       | The starting source node ID.
 | xref:common-usage/running-algos.adoc#common-configuration-relationship-weight-property[relationshipWeightProperty] | String  | null      | yes       | Name of the relationship property to use as weights. If unspecified, the algorithm runs unweighted.
 | objective  | String | 'minimum'  | yes      | If specified, the parameter dictates whether to find the minimum or the maximum weight spanning tree. By default, a minimum weight spanning tree is returned. Permitted values are 'minimum' and 'maximum'.