docs/card-key-provider: fix heading levels and typo
The "ADM PIN" and "SCP02 / SCP03" sub-sections of "Field naming" used the '~' heading character, which Sphinx resolved to level 4 - skipping level 3 and throwing build ERRORs. As a result, both sub-sections had no heading at all. Change both to '^' (level 3) to match the other sub-sections in this file.
While at it, fix a typo: "consisting if" -> "consisting of".
