Update directories for new name of TF-A directories

The TF-A URL was updated, as a result the name of the
directory changed as part of the new git URL and not
all the referenced directories were updated.

Fixes: 0ec0207fe07 ("Update the ARM trusted firmware git URL")
Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
diff --git a/tools/binman/entries.rst b/tools/binman/entries.rst
index a8c0881..3006c59 100644
--- a/tools/binman/entries.rst
+++ b/tools/binman/entries.rst
@@ -197,7 +197,7 @@
 
 To run the tool::
 
-    $ tools/binman/fip_util.py  -s /path/to/arm-trusted-firmware
+    $ tools/binman/fip_util.py  -s /path/to/trusted-firmware-a
     Warning: UUID 'UUID_NON_TRUSTED_WORLD_KEY_CERT' is not mentioned in tbbr_config.c file
     Existing code in 'tools/binman/fip_util.py' is up-to-date