doc: init: add libseccomp version and TODO

It was not clear from the commit 78c92cb what versions of
libseccomp require this kludge.

Looks like the issue in question was fixed by libseccomp commit
88afa50ff7c9787 ("api: force an API level update when necessary") which
made its way to libseccomp v2.5.0.

Amend the comment to tell the version, and add a TODO item to remove the
workaround.

Signed-off-by: Kir Kolyshkin <[email protected]>
Acked-by: Paul Moore <[email protected]>
Signed-off-by: Tom Hromatka <[email protected]>

Author: kolyshkin

seccomp.go

@@ -33,8 +33,9 @@ type VersionError struct {
 
 func init() {
 	// This forces the cgo libseccomp to initialize its internal API support state,
-	// which is necessary on older versions of libseccomp in order to work
+	// which is necessary on older versions of libseccomp (< 2.5.0) in order to work
 	// correctly.
+	// TODO: remove once libseccomp < v2.5.0 is not supported.
 	_, _ = getAPI()
 }