Make tcpdump, wall and useradd match formatting.

pages/common/tcpdump.md

@@ -24,6 +24,5 @@
 
 - capture all traffic except traffic over port 22 and save to a dump file with today's date
 
-```
-tcpdump -w dumpfile.`date +%Y.%m.%d-%H.%M`.pcap not port 22
-```
+`tcpdump -w dumpfile.`date +%Y.%m.%d-%H.%M`.pcap not port 22`
+

pages/common/useradd.md

@@ -4,16 +4,17 @@
 
 - Create new user
 
- `useradd {{name}}`
+`useradd {{name}}`
 
 - Create new user with a default home directory
 
- `useradd -m {{name}}`
+`useradd -m {{name}}`
 
 - Create new user with specified shell
 
- `useradd -s {{/path/to/shell}} {{name}}`
+`useradd -s {{/path/to/shell}} {{name}}`
 
 - Create new user with supplementary groups (mind the lack of whitespace)
 
- `useradd -G {{group1,group2}} {{name}}`
+`useradd -G {{group1,group2}} {{name}}`
+