docs: clarify option's id requirements

Author: EternalRival

stage2/tasks/decision-making-tool/README.md

@@ -216,13 +216,20 @@ The second part of the application (`Decision Picker`) allows you to visualize t
 
 > Refers to any displayed options in the list, including all created and inserted options.
 
+##### `Order number`
+
+1. (+1) Each option's `order number` must be displayed.
+2. (+1) Each option's `order number` must be in `n.` format _(`1.`, `2.`, `3.`, and so on)_.
+3. (+1) Each option's `order number` must reflect its current position in the list.
+
 ##### `id`
 
 1. (+1) Each option's `id` must be displayed.
-2. (+2) Each option's `id` must be unique.
-3. (+2) Each option's `id` must be in `#n` format _(`#1`, `#2`, `#3`, and so on)_.
-4. (+2) Each option's `id` must be generated programmatically at creation _(user cannot change it directly in this element)_.
-5. (+2) When the list of options becomes completely empty, the `id` counter must be reset.
+2. (+1) Each option's `id` must be unique.
+3. (+1) Each option's `id` must be in `#n` format _(`#1`, `#2`, `#3`, and so on)_.
+4. (+1) Each option's `id` must be generated programmatically at creation _(user cannot change it directly in this element)_.
+5. (+1) Each option's `id` must be constant and not affected by deletion of other options.
+6. (+1) When the list of options becomes completely empty, the `id` counter must be reset.
 
 ##### `title`
 
@@ -242,7 +249,7 @@ The second part of the application (`Decision Picker`) allows you to visualize t
 
 ##### Option columns
 
-1. (+2) The width of the "columns" ([`id`](#id), [`title`](#title), [`weight`](#weight), [`delete button`](#delete-button)) should match in "rows" ([`option`](#option-22108)). _(`flex`/`grid`/`table` can be useful here. How you do it is up to you.)_
+1. (+2) The width of the "columns" ([`order number`](#order-number), [`id`](#id), [`title`](#title), [`weight`](#weight), [`delete button`](#delete-button)) should match in "rows" ([`option`](#option-22108)). _(`flex`/`grid`/`table` can be useful here. How you do it is up to you.)_
 
 #### Buttons (34/108)