change formatting

input examples are now given as

```bash
input $ARG1
```

While outputs use md's '> ' sign as a quote.

system/systemd/journal.md

@@ -2,11 +2,15 @@
 title: "journal"
 tags: [ "Documentation", "systemd" ]
 ---
+```
 
 Find errors since November
 
-> journalctl --since=2018-11-01 --grep="EXT4-fs error"
+```bash
+journalctl --since=2018-11-01 --grep="EXT4-fs error"
+```
 
 Limit size to 2G.
 
-> journalctl --vacuum-size=2G
+```bash
+journalctl --vacuum-size=2G