Add timestamp alias

Signed-off-by: Severin Kaderli <severin@kaderli.dev>

system/.config/custom/aliases

@@ -41,9 +41,12 @@ if [ -d "${HOME}/dev/work" ]; then
 fi
 
 # Alias for opening my code editor
-alias e="code"
+alias e='code'
 
 # Work aliases
 if [ -d "${HOME}/dev/work/tools/dde" ]; then
     alias dde='make -f "${HOME}/dev/work/tools/dde/Makefile"'
-fi
+fi
+
+# Other aliases
+alias timestamp='date +%s'