Qiskit-bot local configuration (#851)

Part of #50 

This PR creates the `qiskit_bot.yaml` file to set a local configuration
for the qiskit-bot. The file only contains one rule of notifications.
The rest will be added in a follow-up.

qiskit_bot.yaml

@@ -0,0 +1,15 @@
+---
+# We use quotes around users who don`t want a GitHub notification,
+# but whom we still want their name in the Qiskit Bot message so
+# people know they are relevant.
+notifications:
+  "docs/start/index.mdx":
+    - "@javabster"
+    - "`@abbycross`"
+always_notify: true
+notification_prelude: |
+  Thanks for contributing to Qiskit documentation!
+
+  Before your PR can be merged, it will first need to pass continuous
+  integration tests and be reviewed. Sometimes the review process can be slow,
+  so please be patient.