tee: Add usecase for process substitution (#1584)

pages/common/tee.md

@@ -1,6 +1,6 @@
 # tee
 
-> Read from standard input and write to standard output and files.
+> Read from standard input and write to standard output and files (or commands).
 
 - Copy standard input to each FILE, and also to standard output:
 
@@ -9,3 +9,7 @@
 - Append to the given FILEs, do not overwrite:
 
 `echo "example" | tee -a {{FILE}}`
+
+- Create a folder called "example", count the number of characters in "example" and write "example" to the terminal:
+
+`echo "example" | tee >(xargs mkdir) >(wc -c)`