[FAB-8424] Fix fabric-samples checkout instruction

Fix fabric-samples instructions to cd into
repository before checkout of tag.

Change-Id: I273afb103ea2afe38342bad997d6e1fa8f47b725
Signed-off-by: David Enyeart <enyeart@us.ibm.com>

Author: denyeart

docs/source/samples.rst

@@ -26,10 +26,10 @@ execute the following commands:
 .. code:: bash
 
   git clone -b master https://github.com/hyperledger/fabric-samples.git
-  git checkout {TAG}　
   cd fabric-samples
+  git checkout {TAG}　
 
-.. note:: To ensure the samples are compatible with the version of Fabric binaries you download below, 
+.. note:: To ensure the samples are compatible with the version of Fabric binaries you download below,
           checkout the samples ``{TAG}`` that matches your Fabric version, for example, v1.1.0-alpha.
           To see a list of all fabric-samples tags, use command "git tag".
 
@@ -63,7 +63,7 @@ you will extract the platform-specific binaries:
 
 .. note:: You can use the command above for any published version of Hyperledger
           Fabric. Simply replace '1.1.0-alpha' with the version identifier
-          of the version you wish to install. 
+          of the version you wish to install.
 
 The command above downloads and executes a bash script
 that will download and extract all of the platform-specific binaries you