OIDC primer: distinguish roles more clearly in text

[bblfish]

The spec keeps speaking of a "we" that does something, but the actor that is referred
to shifts from one place to another.
eg. §2 speaks of Alice, "decentphotos" the app but suddenly in §3 the langauge switches to "we"

Now that we have Alice’s OP’s URL, the RP must make a request to retrieve the OP’s configuration.

 So I guess we = "the relying party" (but then it should be "we, the relying party, ..."

until §7 "we" seems to refer to the app, but in §7 we must be referring to "The OpenId Provider"
according to the sequence diagram.

> If an app URI is provided as the client id (see note above to see other options), we must fetch that app URI to confirm its validity.

in §8 "check to be sure" (who checks?)

in §10 "generates a code" - who generates a code? One has to keep looking at the diagram to work that out.