Add a rst syntax check to avoid invalid syntax in the future

- Check rst passes
```
crl-m1:flake8-bugbear cooper$ /tmp/tf/bin/rstcheck README.rst
Success! No issues detected.
crl-m1:flake8-bugbear cooper$ echo $?
0
```
- Chcek we have valid yaml
```
crl-m1:flake8-bugbear cooper$ cat .github/workflows/rst_check.yml | yq > /dev/null
crl-m1:flake8-bugbear cooper$ echo $?
0
```

.github/workflows/rst_check.yml

@@ -0,0 +1,23 @@
+name: rst_check
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Set up Python
+      uses: actions/setup-python@v5
+
+    - name: Update pip and setuptools
+      run: |
+        python -m pip install --upgrade pip setuptools
+
+    - name: Install rstcheck
+      run: |
+        python -m pip install rstcheck
+
+    - name: Run rstcheck
+      run: |
+        rstcheck README.rst