[telepathy-spec/master] Replace rationale for ImmutableStreams with the rationale from the Immutable_Streams pseudo-capability

[Simon McVittie]

I think that one's clearer.
---
 spec/Channel_Type_Streamed_Media.xml |   19 ++++++++++---------
 1 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/spec/Channel_Type_Streamed_Media.xml b/spec/Channel_Type_Streamed_Media.xml
index c881a40..3417063 100644
--- a/spec/Channel_Type_Streamed_Media.xml
+++ b/spec/Channel_Type_Streamed_Media.xml
@@ -572,15 +572,16 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.</
           entries in a contact's capabilities, then user interfaces MAY choose
           to show a separate "call" option for each class of call.</p>
 
-        <tp:rationale>
-          <p>On protocols like XMPP Jingle, it is possible to start an
-            audio-only call and then add a video stream, so the user interface
-            could be a single "call" button, which places an audio call, and an
-            "enable video" button in the call interface. However, on protocols
-            like Google Talk it is not possible to upgrade a call once it has
-            started; the user interface will thus need to adapt in order to
-            allow the user to place video calls.</p>
-        </tp:rationale>
+          <tp:rationale>
+            <p>For example, once an audio-only Google Talk call has started,
+              it is not possible to add a video stream; both audio and video
+              must be requested at the start of the call if video is desired.
+              User interfaces may use this pseudo-capability as a hint to
+              display separate "Audio call" and "Video call" buttons, rather
+              than a single "Call" button with the option to add and remove
+              video once the call has started for contacts without this flag.
+            </p>
+          </tp:rationale>
 
         <p>For incoming channels, this property MUST be included in the channel's immutable properties
           (as announced in <tp:dbus-ref
-- 
1.5.6.5