[SYCL][Doc] Refresh info about releases

Author: AlexeySachkov

sycl/doc/Releases.md

@@ -30,7 +30,10 @@ Release branches are prefixed with `sycl-rel-`
 ### _[Upcoming]_ `6.3.0` release
 
 This release will be made from the
-[`sycl-rel-6_3`](https://github.com/intel/llvm/tree/sycl-rel-6_3) branch.
+[`sycl-rel-6_3`](https://github.com/intel/llvm/tree/sycl-rel-6_3) branch and we
+have the following tags published:
+- [`v6.3.0-rc1`](https://github.com/intel/llvm/releases/tag/v6.3.0-rc1) -
+  release candidate 1 for 6.3.0 release
 
 ### **[Latest]** `6.2.0` release
 
@@ -41,14 +44,22 @@ we have the following tags published:
 - [`v6.2.0-rc1`](https://github.com/intel/llvm/releases/tag/v6.2.0-rc1) -
   release candidate 1 for 6.2.0 release
 
-### `6.1.0` release
+### [Legacy] `6.1.0` release
+
+This is a _legacy_ release meaning that we do not provide support for that
+release branch anymore, no bug fixes (functional or security) will be backported
+to it and now new tags will be made.
 
 This release was made from
 the [`sycl-rel-6_1_0`](https://github.com/intel/llvm/tree/sycl-rel-6_1_0)
 branch and we have the following tags published:
 - [`v6.1.0`](https://github.com/intel/llvm/releases/tag/v6.1.0)
 
-### `6.0.X` releases
+### [Legacy] `6.0.X` releases
+
+This is a _legacy_ release meaning that we do not provide support for that
+release branch anymore, no bug fixes (functional or security) will be backported
+to it and now new tags will be made.
 
 These releases are made from
 the [`sycl-rel-6_0_0`](https://github.com/intel/llvm/tree/sycl-rel-6_0_0)