Some PR feedback corrections

Including adding a hyperlink, although this requires a separate fix that I'll do on a different branch

api/client-server/administrative_contact.yaml

@@ -124,10 +124,15 @@ paths:
       summary: Requests a validation token be sent to the given email address for the purpose of adding an email address to an account
       description: |-
         Proxies the identity server API ``validate/email/requestToken``, but
-        first checks that the given email address is not already associated
+        first checks that the given email address is **not** already associated
         with an account on this Home Server. This API should be used to request
         validation tokens when adding an email address to an account. This API's
-        parameters and response is identical to that of `/register/email/requestToken`.
+        parameters and response is identical to that of the HS API
+        |/register/email/requestToken|_ endpoint.
+
+        .. |/register/email/requestToken| replace:: ``/register/email/requestToken``
+
+        .. _/register/email/requestToken: #post-matrix-client-%CLIENT_MAJOR_VERSION%-register-email-requesttoken
       responses:
         200:
           description: An email was sent to the given address

api/client-server/registration.yaml

@@ -136,6 +136,8 @@ paths:
     post:
       summary: Requests a validation token be sent to the given email address for the purpose of registering an account
       description: |-
+        .. _register-email-requestToken-endpoint:
+
         Proxies the identity server API ``validate/email/requestToken``, but
         first checks that the given email address is not already associated
         with an account on this Home Server. Note that, for consistency,
@@ -247,7 +249,7 @@ paths:
       summary: Requests a validation token be sent to the given email address for the purpose of resetting a user's password
       description: |-
         Proxies the identity server API ``validate/email/requestToken``, but
-        first checks that the given email address is associated with an account
+        first checks that the given email address **is** associated with an account
         on this Home Server. This API should be used to request
         validation tokens when authenticating for the
         `account/password` endpoint. This API's parameters and response are