doc: update pipe/socket examples for --inherit-fd

The syntax of the inherit-fd functionality for unix socket and pipe
includes a colon.

Fixes: 0df3f79fc0 ("criu(8): fix --inherit-fd description")
Fixes: c37324b6d0 ("crtools: describe the inherit-fd option")
Signed-off-by: Mark Polyakov <mark@thundercompute.com>
Signed-off-by: Radostin Stoyanov <rstoyanov@fedoraproject.org>

Documentation/criu.txt

@@ -502,8 +502,8 @@ Restores previously checkpointed processes.
 The 'resource' argument can be one of the following:
 +
     - **tty[**__rdev__**:**__dev__**]**
-    - **pipe[**__inode__**]**
-    - **socket[**__inode__*]*
+    - **pipe:[**__inode__**]**
+    - **socket:[**__inode__*]*
     - **file[**__mnt_id__**:**__inode__**]**
     - 'path/to/file'