Add a README to our examples.

Author: carlosalberto

examples/README.md

@@ -0,0 +1,10 @@
+## Examples
+
+This directory contains examples of tracing applications using the sqlalchemy package. To run the examples, make sure you've installed the packages `opentracing` and `lightstep`. If you have a lightstep token and would like to view the created spans, then uncomment to proper lines under the given examples. If you would like to use a different OpenTracing implementation, you may also replace the lightstep tracer with the tracer of your choice.
+
+Then simply:
+
+```
+> python example-file.py
+```
+