Add reference to example path construction in section 3 intro

[aaronpk]

From Pieter's review:

Would it be possible to include the final result of what the path would look like when inserting the "/.well-known/example-protected-resource" between the host and path components of the protected resource's resource identifier just to remove opportunity for misinterpretation (is this the same as the second example given in Section 3.1, if so, perhaps refer to that example)?

"between the host and path components of the protected resource's resource identifier, as shown in Section 3.1 below"