doc: board: ti: j7200: Fix build step numbering

Fix up build step numbering.

Fixes: c727b81d6530 ("doc: board: ti: k3: Reuse build instructions")
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
1 file changed