Update documentation of related, up-sell and cross-sell products rotation modes

- Update merchant docs

Author: bubasuma

src/images/images/config-catalog-catalog-rule-based-product-relations.png

@@ -22,4 +22,7 @@ For example, suppose you have three rules with a priority of 1, 2, and 3.
 
 If the first rule returns more matching products than allowed by the _configurable maximum limit_, but less than the _real limit_, the matching products from the other existing rules are used (in order of priority) until the _real limit_ is reached.
 
-By priority, the matching products returned from Rule 1 can be used first to fill all 26 available slots. Because Rule 1 returned only two matching products, there is still room for 24 more. Rule 2 has the next highest priority, and returns six more matching products. There are now 18 available slots to be filled. Rule 3 has the next level of priority, with enough matching products to fill the remaining 18 slots. When all available slots are filled, and depending on the rotation mode that is set, the list might be shuffled and then reduced to the configurable maximum limit. In this case, the remaining six products appear in the store.
+By priority, the matching products returned from Rule 1 can be used first to fill all 26 available slots. Because Rule 1 returned only two matching products, there is still room for 24 more. Rule 2 has the next highest priority, and returns six more matching products. There are now 18 available slots to be filled. Rule 3 has the next level of priority, with enough matching products to fill the remaining 18 slots. When all available slots are filled, and depending on the rotation mode that is set, products might be shuffled or ordered by ID inside each priority and then reduced to the configurable maximum limit. In this case, the remaining six products appear in the store.
+
+{: .bs-callout .bs-callout-info}
+Selected products will always display before the rule-based products regardless of the rotation mode.

src/marketing/product-related-rule-priority.md

@@ -25,9 +25,10 @@ The behavior and display of product relationship rules is determined by the conf
         - `Rule-Based Only`
 
     - Set **Rotation Mode for Products in Related Product List** to one of the following:
-
-        - `Do Not Rotate`
-        - `Shuffle`
+    
+        - `By Priority, Then by ID`
+        - `By Priority, Then Random`
+        - `Weighted Random`
 
 1. To complete the cross-sell product settings, do the following:
 
@@ -41,8 +42,9 @@ The behavior and display of product relationship rules is determined by the conf
 
     - Set **Rotation Mode for Products in Cross-Sell Product List** to one of the following:
 
-        - `Do Not Rotate`
-        - `Shuffle`
+        - `By Priority, Then by ID`
+        - `By Priority, Then Random`
+        - `Weighted Random`
 
 1. To complete the up-sell product settings, do the following:
 
@@ -56,7 +58,24 @@ The behavior and display of product relationship rules is determined by the conf
 
     - Set **Rotation Mode for Products in Upsell Product List** to one of the following:
 
-        - `Do Not Rotate`
-        - `Shuffle`
+        - `By Priority, Then by ID`
+        - `By Priority, Then Random`
+        - `Weighted Random`
 
 1. When complete, click <span class="btn">Save Config</span>.
+
+## Rotation Modes Description
+
+{: .rotation-modes-table }
+
+| Mode | Description |
+|---|---|
+| By Priority, Then by ID | Products are sorted by priority and then reordered by ID inside each priority. Products from lower priority rule will show up only when they are no products left from higher priority rule to fill the available slots. |
+| By Priority, Then Random | Products are sorted by priority and then randomized inside each priority. Products from lower priority rule will show up only when they are no products left from higher priority rule to fill the available slots. |
+| Weighted Random | Products are randomized such that products belonging to rule with higher priority will have higher probability to appear than those belonging to rule with lower priority. Products are then reduced to the configurable maximum limit and regrouped back by priority. This mode gives a chance to products from lower priority to appear sometimes even if the remaining slots could be filled up with products from rule with higher priority|
+
+<style>
+.rotation-modes-table td:first-of-type {
+  width: 200px;
+}
+</style>