Make all git clone commands referring to v1.2.0 release branch (#656)

Author: tjanczak

docs/source/dev_guide/advanced_install/advanced_install_guide_compilation.rst

@@ -228,7 +228,7 @@ Step 7: Clone Intel® DL Streamer repository
 .. code:: sh
 
     cd ~
-    git clone https://github.com/open-edge-platform/edge-ai-libraries.git
+    git clone https://github.com/open-edge-platform/edge-ai-libraries.git -b release-1.2.0
     cd edge-ai-libraries
     git submodule update --init libraries/dl-streamer/thirdparty/spdlog