airpaste: add simple examples and clarify existing ones (#2277)

pages/common/airpaste.md

@@ -2,13 +2,21 @@
 
 > Share messages and files on the same network.
 
+- Wait for message and display when received:
+
+`airpaste`
+
+- Send text:
+
+`echo {{text}} | airpaste`
+
 - Send file:
 
-`airpaste < {{file.txt}}`
+`airpaste < {{path/to/file}}`
 
 - Receive file:
 
-`airpaste > {{file.txt}}`
+`airpaste > {{path/to/file}}`
 
 - Create/Join channel: