[editorial] Fix FaaS capitalization (#4369)

Author: chalin

specification/protocol/file-exporter.md

@@ -27,7 +27,7 @@ Currently, it only describes the serialization of OpenTelemetry data to the OTLP
 
 Why do we need a file exporter - why not just use the OTLP exporter?
 
-- *Faas*: In a FaaS environment, the OTLP exporter may not be able to send data to a collector.
+- *FaaS*: In a FaaS environment, the OTLP exporter may not be able to send data to a collector.
 - *Consistent log scraping from pods*: In a Kubernetes environment, logs are often scraped from the stdout pod file.
   This exporter can be used to write logs to stdout - which makes it easier to integrate with existing log scraping tools.
   Existing solutions add metadata, such as the trace ID, to the log line,