fix: SpecGen3: Render global tag descriptions if available

[WoH]

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[endor]

I wonder whether we should do some verification on the data the user provides to make sure it fits with the OpenAPI 3 specification.

[WoH]

I wonder whether we should do some verification on the data the user provides to make sure it fits with the OpenAPI 3 specification.

Valid OAS3 Tags[] in case specVersion: 3 and valid OAS2 Tags[] in case specVersion: 2, but I'd agree that we may want to improve the support. Don't think it has to be part of this PR though.