Clarify font mapping for deprecated fonts (#1019)

BUG: Montserrat is missing from the font enum list. Not quite sure how
to add.

---------

content/en-us/reference/engine/enums/Font.yaml

@@ -21,13 +21,13 @@ items:
   - name: Arial
     value: 1
     summary: |
-      Arial has been removed from Roblox. Use Arimo instead.
+      Arial has been removed from Roblox. Using Arial will map to Arimo.
     tags: []
     deprecation_message: ''
   - name: ArialBold
     value: 2
     summary: |
-      Arial has been removed from Roblox. Use Arimo instead.
+      Arial has been removed from Roblox. Using Arial will map to Arimo.
     tags: []
     deprecation_message: ''
   - name: SourceSans
@@ -117,25 +117,25 @@ items:
   - name: Gotham
     value: 17
     summary: |
-      Gotham has been removed from Roblox. Use Montserrat instead.
+      Gotham has been removed from Roblox. Using Gotham will map to Montserrat.
     tags: []
     deprecation_message: ''
   - name: GothamMedium
     value: 18
     summary: |
-      Gotham has been removed from Roblox. Use Montserrat instead.
+      Gotham has been removed from Roblox. Using Gotham will map to Montserrat.
     tags: []
     deprecation_message: ''
   - name: GothamBold
     value: 19
     summary: |
-      Gotham has been removed from Roblox. Use Montserrat instead.
+      Gotham has been removed from Roblox. Using Gotham will map to Montserrat.
     tags: []
     deprecation_message: ''
   - name: GothamBlack
     value: 20
     summary: |
-      Gotham has been removed from Roblox. Use Montserrat instead.
+      Gotham has been removed from Roblox. Using Gotham will map to Montserrat.
     tags: []
     deprecation_message: ''
   - name: AmaticSC