top.md: various tweaks (#923)

- standardize examples to use generic tokens
- format tokens using snake_case
- use "show" for all example descriptions, for consistency
- reword the descriptions for additional clarity.

pages/linux/top.md

@@ -10,13 +10,13 @@
 
 `top -i`
 
-- List processes owned by given user:
+- Show only processes owned by given user:
 
-`top -u {{user-name}}`
+`top -u {{user_name}}`
 
-- List processes by PID. It takes a comma separated list. (Normally you wouldn't know PIDs off hand. This example picks the PIDs from the process name):
+- Show only the processes with the given PID(s), passed as a comma-separated list. (Normally you wouldn't know PIDs off hand. This example picks the PIDs from the process name):
 
-`top -p $(pgrep -d ',' {{nginx}})`
+`top -p $(pgrep -d ',' {{process_name}})`
 
 - Get help about interactive commands: