Docs: Fix an error in Windows command

Signed-off-by: Anton Komlev <anton.komlev@arm.com>
Change-Id: Id2089de7e819c7dcc49e8c596f352e3bdd7e5490
diff --git a/docs/getting_started/tfm_getting_started.rst b/docs/getting_started/tfm_getting_started.rst
index 4815c97..128b05a 100644
--- a/docs/getting_started/tfm_getting_started.rst
+++ b/docs/getting_started/tfm_getting_started.rst
@@ -99,7 +99,7 @@
 
         .. code-block:: bash
 
-            set PATH=<CMake_Path>\bin;$PATH
+            set PATH=<CMake_Path>\bin;%PATH%
 
 ###########################
 Install python dependencies
@@ -176,7 +176,7 @@
 
                 .. code-block:: bash
 
-                    set PATH=<ARM_CLANG_PATH>\bin;$PATH
+                    set PATH=<ARM_CLANG_PATH>\bin;%PATH%
                     set ARM_PRODUCT_PATH=<ARM_CLANG_PATH>\sw\mappings
 
               - Configure proper tool variant and license.
@@ -209,7 +209,7 @@
 
                 .. code-block:: bash
 
-                    export PATH=<GNU_ARM_PATH>\bin;$PATH
+                    set PATH=<GNU_ARM_PATH>\bin;%PATH%
 
       .. note::
 
@@ -237,7 +237,7 @@
 
                 .. code-block:: bash
 
-                    export PATH=<IAR_COMPILER_PATH>\bin;$PATH
+                    set PATH=<IAR_COMPILER_PATH>\bin;%PATH%
 
 #############################
 Build AN521 regression sample