Make docs more visible from home page
Add links to the other documents to the homepage at `index.md`. Clean
up some of these other documents (including converting the Zephyr test
plan to markdown).
Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/docs/imgtool.md b/docs/imgtool.md
index a4f5c40..27f41b8 100644
--- a/docs/imgtool.md
+++ b/docs/imgtool.md
@@ -1,4 +1,4 @@
-## Image tool
+# Image tool
The Python program `scripts/imgtool.py` can be used to perform the
operations that are necessary to manage keys and sign images. Using