README: Add link to future release plans

This commit adds a link to the "Release Plan" document in the wiki,
which provides information about the planned future releases.

It also updates the link to the release list page to point to the "tags"
page, which is more convenient when browsing by the release version.

Signed-off-by: Stephanos Ioannidis <[email protected]>

Author: stephanosio

README.md

@@ -33,9 +33,12 @@ The Zephyr SDK bundle releases are available for the following host platforms:
 - macOS (AArch64, x86-64)
 - Windows (x86-64)
 
-These binaries can be downloaded from here:
+These binaries can be downloaded from
+[here](https://github.com/zephyrproject-rtos/sdk-ng/tags).
 
-https://github.com/zephyrproject-rtos/sdk-ng/releases
+For future release plans, please refer to the
+[Release Plan](https://github.com/zephyrproject-rtos/sdk-ng/wiki/Release-Plan)
+document in the wiki.
 
 ## Build Process