[Openid-specs-fapi] Issue #623: Replace reference to obsolete RFC7525 with BCP195 (openid/fapi)

[josephheenan]

New issue 623: Replace reference to obsolete RFC7525 with BCP195
https://bitbucket.org/openid/fapi/issues/623/replace-reference-to-obsolete-rfc7525-with

Joseph Heenan:

In  the TLS section FAPI2SP references RFC7525, which is now obsolete.

I think we should reference [https://www.rfc-editor.org/info/bcp195](https://www.rfc-editor.org/info/bcp195) directly instead.