doc: Release notes for v2.1 - initial (empty) draft

Get things started for Zephyr 2.1 release notes.
Individual PRs will update their appropriate sections.

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>

doc/releases/release-notes-2.1.rst

@@ -0,0 +1,80 @@
+:orphan:
+
+.. _zephyr_2.1:
+
+Zephyr Kernel 2.1.0 (Working Draft)
+####################################
+
+We are pleased to announce the release of Zephyr kernel version 2.1.0.
+
+Major enhancements with this release include:
+
+* TBD
+
+The following sections provide detailed lists of changes by component.
+
+Kernel
+******
+
+* TBD
+
+Architectures
+*************
+
+* TBD
+
+Boards & SoC Support
+********************
+
+* TBD
+
+Drivers and Sensors
+*******************
+
+* TBD
+
+Networking
+**********
+
+* TBD
+
+Bluetooth
+*********
+
+* TBD
+
+Build and Infrastructure
+************************
+
+* TBD
+
+Libraries / Subsystems
+***********************
+
+* TBD
+
+HALs
+****
+
+* TBD
+
+Documentation
+*************
+
+* TBD
+
+Tests and Samples
+*****************
+
+* TBD
+
+Issue Related Items
+*******************
+
+These GitHub issues were addressed since the previous 2.0.0 tagged
+release:
+
+.. comment  List derived from GitHub Issue query: ...
+   * :github:`issuenumber` - issue title
+
+* :github:`99999` - issue title