Update body/transfer size unit from string -> number (#833)

Author: AbhiPrasad

develop-docs/sdk/performance/span-data-conventions.mdx

@@ -24,6 +24,6 @@ Below describes the conventions for the Span interface for the `data` field on t
 | `url`               | string | The URL of the resource that was fetched.  | `https://example.com` |
 | `method`            | string | The HTTP method used.                      | `GET`                 |
 | `type`              | string | The type of the resource that was fetched. | `xhr`                 |
-| `Encoded Body Size` | string | The encoded body size of the request.      | `123 B`               |
-| `Decoded Body Size` | string | The decoded body size of the request.      | `456 B`               |
-| `Transfer Size`     | string | The transfer size of the request.          | `789 B`               |
+| `Encoded Body Size` | number | The encoded body size of the request.      | `123`                 |
+| `Decoded Body Size` | number | The decoded body size of the request.      | `456`                 |
+| `Transfer Size`     | number | The transfer size of the request.          | `789`                 |