Update README for newly-added folders

- Document tests/, tflm/, sort the list of directories.

Change-Id: I93cb96a058a413a4d93dba7e71242cec32acf488

README.md

diff --git a/README.md b/README.md
index bdd0cf8..299d223 100644
--- a/README.md
+++ b/README.md
@@ -21,10 +21,12 @@
 * build_tools: Build tool/rules for both Bazel and CMake
 * crt: Kelvin BSP
 * examples: Source code to build Kelvin SW artifacts.
+* host_tools: host tool to generate the intrinsic header and toolchain op files
 * platforms: Crosscompile platform setup for Bazel.
+* tests: Tests to exercise features of the Kelvin core.
+* tflm: Support code and optimized routines for TFLM.
 * third_party: Third party repositories for Bazel.
 * toolchains: Crosscomple toolchain setup for Bazel.
-* host_tools: host tool to generate the intrinsic header and toolchain op files
 
 ## Build the project