config-linux: Use the implicit link name shortcut

727e64d (config-linux.md: fix wrong link description about cgroups,
2017-05-14, opencontainers#826) added a redundant link name for libseccomp.  This
commit restores the old implicit link name shortcut [1] there and
updates the other entries (all of which were for the filesystems table
in config-linux) that could also use that shortcut.  This is obviously
not a major change, but I think it makes the source easier to read by
minimizing the markup so you can focus on the text.

[1]: https://daringfireball.net/projects/markdown/syntax#link

Signed-off-by: W. Trevor King <wking@tremily.us>

Author: wking

config-linux.md

@@ -12,10 +12,10 @@ The following filesystems SHOULD be made available in each container's filesyste
 
 | Path     | Type   |
 | -------- | ------ |
-| /proc    | [procfs][procfs]   |
-| /sys     | [sysfs][sysfs]     |
-| /dev/pts | [devpts][devpts]   |
-| /dev/shm | [tmpfs][tmpfs]     |
+| /proc    | [procfs][] |
+| /sys     | [sysfs][]  |
+| /dev/pts | [devpts][] |
+| /dev/shm | [tmpfs][]  |
 
 ## <a name="configLinuxNamespaces" />Namespaces
 
@@ -510,7 +510,7 @@ For more information, see the [sysctl(8)][sysctl.8] man page.
 Seccomp provides application sandboxing mechanism in the Linux kernel.
 Seccomp configuration allows one to configure actions to take for matched syscalls and furthermore also allows matching on values passed as arguments to syscalls.
 For more information about Seccomp, see [Seccomp][seccomp] kernel documentation.
-The actions, architectures, and operators are strings that match the definitions in seccomp.h from [libseccomp][libseccomp] and are translated to corresponding values.
+The actions, architectures, and operators are strings that match the definitions in seccomp.h from [libseccomp][] and are translated to corresponding values.
 
 **`seccomp`** (object, OPTIONAL)