Add cheatsheet perl

cheat/cheatsheets/perl

@@ -0,0 +1,8 @@
+# To view the perl version:
+perl -v
+
+# Replace string "\n" to newline
+echo -e "foo\nbar\nbaz" | perl -pe 's/\n/\\n/g;'
+
+# Replace newline with multiple line to space
+cat test.txt | perl -0pe "s/test1\ntest2/test1 test2/m"