doc: board: ti: am62x: 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>
Revieed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/doc/board/ti/am62x_sk.rst b/doc/board/ti/am62x_sk.rst
index 42b37f9..d7437c6 100644
--- a/doc/board/ti/am62x_sk.rst
+++ b/doc/board/ti/am62x_sk.rst
@@ -103,13 +103,13 @@
 
 3. U-Boot:
 
-* 4.1 R5:
+* 3.1 R5:
 
 .. include::  ../ti/k3.rst
     :start-after: .. k3_rst_include_start_build_steps_spl_r5
     :end-before: .. k3_rst_include_end_build_steps_spl_r5
 
-* 4.2 A53:
+* 3.2 A53:
 
 .. include::  ../ti/k3.rst
     :start-after: .. k3_rst_include_start_build_steps_uboot