doc: board: ti: am62x: provide image alt texts

Provide alternative texts for images.

Fixes: 34f76921d801 ("doc: board: ti: am62x: Convert the image format to svg")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
diff --git a/doc/board/ti/am62x_sk.rst b/doc/board/ti/am62x_sk.rst
index 5ed17c0..42b37f9 100644
--- a/doc/board/ti/am62x_sk.rst
+++ b/doc/board/ti/am62x_sk.rst
@@ -47,6 +47,7 @@
 Below is the pictorial representation of boot flow:
 
 .. image:: img/boot_diagram_k3_current.svg
+  :alt: Boot flow diagram
 
 - Here TIFS acts as master and provides all the critical services. R5/A53
   requests TIFS to get these services done as shown in the above diagram.
@@ -141,10 +142,12 @@
 - tiboot3.bin
 
 .. image:: img/multi_cert_tiboot3.bin.svg
+  :alt: tiboot3.bin image format
 
 - tispl.bin
 
 .. image:: img/dm_tispl.bin.svg
+  :alt: tispl.bin image format
 
 A53 SPL DDR Memory Layout
 -------------------------