[Openid-specs-fapi] Issue #537: Document trade-offs between DPoP and MTLS (openid/fapi)

[dgtonge]

New issue 537: Document trade-offs between DPoP and MTLS
https://bitbucket.org/openid/fapi/issues/537/document-trade-offs-between-dpop-and-mtls

Dave Tonge:

In relation to  [https://bitbucket.org/openid/fapi/pull-requests/365](https://bitbucket.org/openid/fapi/pull-requests/365) we discussed that it might be helpful to document some of the trade offs between DPoP and MTLS