Updated Compile from source in Linux (markdown)

Compile-from-source-in-Linux.md

@@ -258,8 +258,9 @@ Prerequisites:
 </code></pre>
 <pre><code>cd /opt/build
 git clone https://github.com/EttusResearch/uhd.git
+git fetch origin UHD-4.0
+git checkout UHD-4.0
 cd uhd/host
-git checkout v4.0.0.0
 mkdir build
 cd build
 cmake -DCMAKE_INSTALL_PREFIX=/opt/install/uhd ../