Add clarification to buffer.create (#1237)

## Changes

Specifies the size format.

## Validation

The size format is never specified, I figured the following from my own
tests.
Negative integer: Error while creating buffer.
Positive double: The number is floored, and the extra bits are ignored.

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---------

Co-authored-by: Andrew Etter <[email protected]>

Author: TheAlizabeth

content/en-us/reference/engine/libraries/buffer.yaml

@@ -47,7 +47,7 @@ functions:
         type: number
         default:
         summary: |
-          Size of the buffer.
+          Size of the buffer in bytes. Must be a positive integer.
     returns:
       - type: buffer
         summary: ''