Fix readme formatting and markdown (#2576)

Author: lzchen

Diff for: processor/opentelemetry-processor-baggage/README.rst

@@ -26,7 +26,7 @@ configured. If the external services also have a Baggage span
 processor, the keys and values will appear in those child spans as
 well.
 
-⚠ Warning ⚠️
+[!WARNING]
 
 Do not put sensitive information in Baggage.
 
@@ -39,25 +39,32 @@ Add the span processor when configuring the tracer provider.
 
 To configure the span processor to copy all baggage entries during configuration:
 
-```python
-from opentelemetry.processor.baggage import BaggageSpanProcessor, ALLOW_ALL_BAGGAGE_KEYS
+::
+
+    from opentelemetry.processor.baggage import BaggageSpanProcessor, ALLOW_ALL_BAGGAGE_KEYS
+
+    tracer_provider = TracerProvider()
+    tracer_provider.add_span_processor(BaggageSpanProcessor(ALLOW_ALL_BAGGAGE_KEYS))
 
-tracer_provider = TracerProvider()
-tracer_provider.add_span_processor(BaggageSpanProcessor(ALLOW_ALL_BAGGAGE_KEYS))
-```
 
 Alternatively, you can provide a custom baggage key predicate to select which baggage keys you want to copy.
 
 For example, to only copy baggage entries that start with `my-key`:
 
-```python
-starts_with_predicate = lambda baggage_key: baggage_key.startswith("my-key")
-tracer_provider.add_span_processor(BaggageSpanProcessor(starts_with_predicate))
-```
+::
+
+    starts_with_predicate = lambda baggage_key: baggage_key.startswith("my-key")
+    tracer_provider.add_span_processor(BaggageSpanProcessor(starts_with_predicate))
+
 
 For example, to only copy baggage entries that match the regex `^key.+`:
 
-```python
-regex_predicate = lambda baggage_key: baggage_key.startswith("^key.+")
-tracer_provider.add_span_processor(BaggageSpanProcessor(regex_predicate))
-```
+::
+
+    regex_predicate = lambda baggage_key: baggage_key.startswith("^key.+")
+    tracer_provider.add_span_processor(BaggageSpanProcessor(regex_predicate))
+
+
+References
+----------
+* `OpenTelemetry Project <https://opentelemetry.io/>`_