dm: doc: Update documentation for new driver model schema

Now that Linux has accepted these tags, move U-Boot over to use them.
Tidy up the comments and formatting, making sure that VPL is mentioned
too.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/README.TPL b/doc/README.TPL
index 72027fd..95b466e 100644
--- a/doc/README.TPL
+++ b/doc/README.TPL
@@ -35,8 +35,8 @@
 board config file.
 
 TPL use a small device tree (u-boot-tpl.dtb), containing only the nodes with
-the pre-relocation properties: 'u-boot,dm-pre-reloc' and 'u-boot,dm-tpl'
-(see README.SPL for details).
+the pre-relocation properties: 'bootph-all' and 'bootph-pre-sram'
+(see doc/develop/spl.rst for details).
 
 For example: