[llvm][TableGen][Jupyter] Add notebook links to README

This folder contains the kernel and notebooks
so let's make that obvious and list them in the
readme.

Author: DavidSpickett

llvm/utils/TableGen/jupyter/README.md

@@ -1,4 +1,19 @@
-# A Jupyter kernel for TableGen (llvm-tblgen)
+# Jupyter Tools for TableGen
+
+This folder contains notebooks relating to TableGen and a Jupyter kernel for
+TableGen.
+
+## Notebooks
+
+[LLVM_TableGen.ipynb](LLVM_TableGen.ipynb) - A demo of the kernel's capabilities.
+
+[sql_query_backend.ipynb](sql_query_backend.ipynb) - How to write a backend using
+JSON output and Python.
+
+Notebooks can be viewed in browser on Github or downloaded and run locally. If
+that is not possible, there are Markdown versions next to the notebook files.
+
+## TableGen Kernel
 
 To use the kernel, first install it into jupyter:
 
@@ -23,9 +38,6 @@ Then run one of:
     jupyter console --kernel tablegen
 ```
 
-If you just want to see the results of the notebook, you can read
-[`LLVM_TableGen.md`](LLVM_TableGen.md) instead.
-
 `llvm-tblgen` is expected to be either in the `PATH` or you can set
 the environment variable `LLVM_TBLGEN_EXECUTABLE` to point to it directly.