fixup! config: base GID must be present in the supplementary GIDs array

Author: neersighted

config.md

@@ -233,8 +233,7 @@ For POSIX platforms the `user` structure has the following fields:
 
 On a POSIX platform, processes have both a 'base' GID (as specified in the `gid` field), and an array of supplementary group IDs as described in [IEEE Std 1003.1-2008][ieee-1003.1.2008-xbd-c3.378].
 Runtimes MUST ensure that all group IDs listed defined by `gid` and `additionalGids` are present in the array of supplementary group IDs.
-If the base GID (as specified in the `gid` field) is not present in `additionalGids`, Runtimes SHOULD place the base GID at the start of the supplementary group array. If the base GID is present in `additionalGids`, no additional action is required.
-In all cases, Runtimes SHOULD preserve the order of `additionalGids`.
+Runtimes SHOULD preserve the order of `additionalGids`; when the base GID (as specified in the `gid` field) is absent from `additionalGids`, it SHOULD be positioned at the start of the supplementary group ID array.
 
 Entities which create a container using a runtime on a POSIX platform SHOULD duplicate the base GID (as specified in the `gid` field) as `additionalGids[0]`; this maximizes compatibility and consistency when using runtimes that target a previous version of this specification.