dev-manual: correct misspelled reference to sstate-cache-management.py

(From yocto-docs rev: 3728eea352f8b326ff411aa0f20bfd433ccc7cfa)

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/dev-manual/disk-space.rst

@@ -52,7 +52,7 @@ such as BSD based NAS::
    sstate-cache-management.py --remove-duplicated --cache-dir=sstate-cache
 
 This command will ask you to confirm the deletions it identifies.
-Run ``sstate-cache-management.sh`` for more details about this script.
+Run ``sstate-cache-management.py`` for more details about this script.
 
 .. note::