Make Enum.Font and DataType.Font reference each other (#942)

## Changes

Adds a `See Also` tag to both the `Font` enum and DataType linking them
together.

Created to solve DevForum Documentation Request;
https://devforum.roblox.com/t/clarify-differences-between-%E2%80%98font%E2%80%99-datatype-and-enum-in-documentation/3181603

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---------

Author: metatablecat

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

@@ -14,6 +14,9 @@ description: |
   `Datatype.Font` is used by the `Class.TextLabel.FontFace`,
   `Class.TextButton.FontFace`, and `Class.TextBox.FontFace` properties.
 
+  See also `Enum.Font` as an older alternative to this datatype that is required by some
+  methods and properties (note that most fonts cannot be represented with this enum).
+
   #### Font List
 
   | Name               | Asset ID                                          | Weights                                                                       |

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

@@ -4,6 +4,9 @@ summary: ''
 description: |
   The `Enum.Font` enum is used in `Class.TextBox`, `Class.TextLabel`, and
   `Class.TextButton` to determine how the GUI element will render its text.
+
+  See also `Datatype.Font` as a newer alternative to this enum which encapsulates fonts
+  as a datatype and provides access to more fonts than this enum allows.
 code_samples:
 tags: []
 deprecation_message: ''