doc: Fix netplan-generate.md formatting (#483)

* bullet point removal

There was a single bullet point that divided a sentence. I removed it because I thought it was a typo.

doc/netplan-generate.md

@@ -58,8 +58,8 @@ There are 3 locations that **`netplan generate`** considers:
  * `/run/netplan/*.yaml`
 
 If there are multiple files with exactly the same name, then only one
-will be read. A file in `/run/netplan` will shadow - completely replace
-- a file with the same name in `/etc/netplan`. A file in `/etc/netplan`
+will be read. A file in `/run/netplan` will shadow (completely replace)
+a file with the same name in `/etc/netplan`. A file in `/etc/netplan`
 will itself shadow a file in `/lib/netplan`.
 
 Or, in other words, `/run/netplan` is top priority, then `/etc/netplan`,