README: update manual list and names, online docs URL

Minor tweaks to top-level README:
  - add missing line for overview manual
  - correct manual names to match their *actual* names
  - point reader at docs.yoctoproject.org for online docs

(From yocto-docs rev: 0ce9097728dbdca926fdf7065490207d09a34cb0)

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Reviewed-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/README

@@ -34,26 +34,21 @@ Manual Organization
 
 Here the folders corresponding to individual manuals:
 
-* sdk-manual           - The Yocto Project Software Development Kit (SDK) Developer's Guide.
-* bsp-guide            - The Yocto Project Board Support Package (BSP) Developer's Guide
-* dev-manual           - The Yocto Project Development Tasks Manual
-* kernel-dev           - The Yocto Project Linux Kernel Development Tasks Manual
-* ref-manual           - The Yocto Project Reference Manual
-* brief-yoctoprojectqs - The Yocto Project Quick Start
-* profile-manual       - The Yocto Project Profile and Tracing Manual
-* toaster-manual       - The Toaster Manual
-* test-manual          - The Test Environment Manual
+* overview-manual      - Yocto Project Overview and Concepts Manual
+* sdk-manual           - Yocto Project Software Development Kit (SDK) Developer's Guide.
+* bsp-guide            - Yocto Project Board Support Package (BSP) Developer's Guide
+* dev-manual           - Yocto Project Development Tasks Manual
+* kernel-dev           - Yocto Project Linux Kernel Development Manual
+* ref-manual           - Yocto Project Reference Manual
+* brief-yoctoprojectqs - Yocto Project Quick Start
+* profile-manual       - Yocto Project Profiling and Tracing Manual
+* toaster-manual       - Toaster User Manual
+* test-manual          - Yocto Project Test Environment Manual
 
 Each folder is self-contained regarding content and figures.
 
 If you want to find HTML versions of the Yocto Project manuals on the web,
-go to https://www.yoctoproject.org and click on the "Docs" tab.  From
-there you have access to archived documentation from previous releases, current
-documentation for the latest release, and "Docs in Progress" for the release
-currently being developed.
-
-In general, the Yocto Project site (https://www.yoctoproject.org) is a great
-reference for both information and downloads.
+the current versions reside at https://docs.yoctoproject.org.
 
 poky.yaml
 =========