Merge pull request #30130 from zraexy/docs-update

docs: 17.03 -> 17.09

README.md

···
 ```
 
 For stability and maximum binary package support, it is recommended to maintain
-custom changes on top of one of the channels, e.g. `nixos-17.03` for the latest
+custom changes on top of one of the channels, e.g. `nixos-17.09` for the latest
 release and `nixos-unstable` for the latest successful build of master:
 
 ```
 % git remote update channels
-% git rebase channels/nixos-17.03
+% git rebase channels/nixos-17.09
 ```
 
 For pull-requests, please rebase onto nixpkgs `master`.
···
 * [Manual (NixOS)](https://nixos.org/nixos/manual/)
 * [Nix Wiki](https://nixos.org/wiki/) (deprecated, see milestone ["Move the Wiki!"](https://github.com/NixOS/nixpkgs/issues?q=is%3Aopen+is%3Aissue+milestone%3A%22Move+the+wiki%21%22))
 * [Continuous package builds for unstable/master](https://hydra.nixos.org/jobset/nixos/trunk-combined)
-* [Continuous package builds for 17.03 release](https://hydra.nixos.org/jobset/nixos/release-17.03)
+* [Continuous package builds for 17.09 release](https://hydra.nixos.org/jobset/nixos/release-17.09)
 * [Tests for unstable/master](https://hydra.nixos.org/job/nixos/trunk-combined/tested#tabs-constituents)
-* [Tests for 17.03 release](https://hydra.nixos.org/job/nixos/release-17.03/tested#tabs-constituents)
+* [Tests for 17.09 release](https://hydra.nixos.org/job/nixos/release-17.09/tested#tabs-constituents)
 
 Communication:
 

maintainers/scripts/hydra-eval-failures.py

···
 @click.command()
 @click.option(
     '--jobset',
-    default="nixos/release-17.03",
-    help='Hydra project like nixos/release-17.03')
+    default="nixos/release-17.09",
+    help='Hydra project like nixos/release-17.09')
 def cli(jobset):
     """
     Given a Hydra project, inspect latest evaluation