<, >, |, $: add page (#13846)

Co-authored-by: Sebastiaan Speck <12570668+sebastiaanspeck@users.noreply.github.com>
Co-authored-by: Wiktor Perskawiec <git@spageektti.cc>
Co-authored-by: Lena <126529524+acuteenvy@users.noreply.github.com>

pages/common/less-than.md

@@ -0,0 +1,9 @@
+# Less than
+
+> Redirect a file to `stdin`.
+> Achieves the same effect as `cat file.txt |`.
+> More information: <https://gnu.org/software/bash/manual/bash.html#Redirecting-Input>.
+
+- Redirect a file to `stdin`:
+
+`{{command}} < {{path/to/file.txt}}`