echo: added -n, -e examples (#963)

pages/common/echo.md

@@ -9,3 +9,11 @@
 - Print a message with environment variables:
 
 `echo {{"My path is $PATH"}}`
+
+- Print a message without the trailing newline:
+
+`echo -n {{"Hello World"}}`
+
+- Enable interpretation of backslash escapes (special characters):
+
+`echo -e {{"Column 1\tColumn 2"}}`