Document reconfig of repository, after adding SSH key.

doc/Git_Access.txt

@@ -38,7 +38,13 @@ cat ~/.ssh/id_rsa.pub
 --------------------------------------------------------------
 
 and transmit us the content of the `id_rsa.pub` file, for shared-key
-authentication. Then:
+authentication. Then, if you already have a cloned repository, run:
+
+--------------------------------------------------------------
+git-config remote.origin.url git+ssh://sflphone_org@sflphone.org/git/sflphone.git
+--------------------------------------------------------------
+
+Otherwise, grab a new copy:
 
 --------------------------------------------------------------
 git clone git+ssh://sflphone_org@sflphone.org/git/sflphone.git
@@ -46,3 +52,4 @@ cd sflphone
 autoreconf --install
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+