Apply suggestions from code review

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

data/api/client-server/login.yaml

@@ -184,7 +184,7 @@ paths:
                   The lifetime of the access token, in milliseconds. Once
                   the access token has expired a new access token can be
                   obtained by using the provided refresh token. If no
-                  refresh token is provided, the client will need re-log in
+                  refresh token is provided, the client will need to re-log in
                   to obtain a new access token. If not given, the client can
                   assume that the access token will not expire.
                 x-addedInMatrixVersion: "1.3"

data/api/client-server/refresh.yaml

@@ -45,8 +45,8 @@ paths:
         The old refresh token remains valid until the new access token or refresh token
         is used, at which point the old refresh token is revoked.
 
-        Note that this endpoint does not require authentication, since
-        authentication is provided via the refresh token.
+        Note that this endpoint does not require authentication via an
+        access token. Authentication is provided via the refresh token.
 
         Application Service identity assertion is disabled for this endpoint.
       operationId: refresh

data/api/client-server/registration.yaml

@@ -173,7 +173,7 @@ paths:
                   The lifetime of the access token, in milliseconds. Once
                   the access token has expired a new access token can be
                   obtained by using the provided refresh token. If no
-                  refresh token is provided, the client will need re-log in
+                  refresh token is provided, the client will need to re-log in
                   to obtain a new access token. If not given, the client can
                   assume that the access token will not expire.