Update source to coming soon

Author: dustin-decker

README.md

@@ -93,7 +93,7 @@ TruffleHog has a sub-command for each source of data that you may want to scan:
 - gitlab
 - S3
 - filesystem
-- file and stdin
+- file and stdin (coming soon)
 
 Each subcommand can have options that you can see with the `-h` flag provided to the sub command: