fix(grid): Update responsive docs to have accurate class prefixes (#3175)

Author: Ayesha Mazumdar

ui/utilities/grid/docs.mdx

@@ -250,9 +250,9 @@ Below is an overview table outlining the default behavior for columns and how th
 
 |   |Default|Small (>= 480px)|Medium (>=768px)|Large (>=1024px)|
 |---|---|---|---|---|
-|Width class prefix|`slds-size`|`slds-size-small`|`slds-size-medium`|`slds-size-large`|
+|Width class prefix|`slds-size`|`slds-small-size`|`slds-medium-size`|`slds-large-size`|
 |# of columns|1,2,3,4,5,6,7,8 and 12
-|Column ordering prefix|`slds-order`|`slds-order-small`|`slds-order-medium`|`slds-order-large`|
+|Column ordering prefix|`slds-order`|`slds-small-order`|`slds-medium-order`|`slds-large-order`|
 |Max # of reorders|12
 
 <Blockquote>