[File Structure] Clarify name convention is optional
Liz Lynch found wording confusing.
Use "MAY" to indicate this is optional.
MODIFY
versions/3.0.md
versions/3.0.md
@@ -139,7 +139,7 @@ The OAS representation of the API is made of a single file.
However, parts of the definitions can be split into separate files, at the discretion of the user.
This is applicable for `$ref` fields in the specification as follows from the [JSON Schema](http://json-schema.org) definitions.
-By convention, the OpenAPI Specification (OAS) file is named `openapi.json` or `openapi.yaml`.
+By convention, the OpenAPI Specification (OAS) file MAY be named `openapi.json` or `openapi.yaml`.
### Data Types

[File Structure] Clarify name convention is optional

Liz Lynch found wording confusing.  

Use "MAY" to indicate this is optional.

Signed-off-by: Rob Dolin <robdolin@microsoft.com>