[DOC] fix activities table in bpmn support doc (#637)

Add missing implementation status icon for script task which broke the table.
This issue has been introduced by 6e19835

docs/bpmn-support.adoc

@@ -78,6 +78,7 @@ The default rendering uses `white` as fill color and `black` as stroke color.
 *icon*: the task icon is derived from the https://thenounproject.com/term/hand/7660/[noun project 'hand' icon] by João Miranda, licensed as https://creativecommons.org/licenses/by/3.0/us/legalcode[Creative Commons CCBY 3.0]
 
 |Script Task
+|icon:check-circle-o[]
 |Icon may be subject to change +
 *icon*: the task icon is derived from the https://thenounproject.com/term/script/2331578/[noun project 'script' icon] by Sérgio Filipe Cardoso Pires, licensed as https://creativecommons.org/licenses/by/3.0/us/legalcode[Creative Commons CCBY 3.0]