fix frontpage readme

fix frontpage readme, somehow /.github/README.md is used on front page instead of /README.md file

.mapping.json

@@ -3,7 +3,6 @@
   ".clang-tidy":"cloud/blockstore/github_toplevel/.clang-tidy",
   ".github/.arcignore":"cloud/blockstore/github_toplevel/.github/.arcignore",
   ".github/.gitignore":"cloud/blockstore/github_toplevel/.github/.gitignore",
-  ".github/README.md":"cloud/blockstore/github_toplevel/.github/README.md",
   ".github/actions/build/action.yaml":"cloud/blockstore/github_toplevel/.github/actions/build/action.yaml",
   ".github/actions/prepare/action.yaml":"cloud/blockstore/github_toplevel/.github/actions/prepare/action.yaml",
   ".github/actions/s3cmd/action.yaml":"cloud/blockstore/github_toplevel/.github/actions/s3cmd/action.yaml",
@@ -46,6 +45,7 @@
   ".github/terraform/provider.tf":"cloud/blockstore/github_toplevel/.github/terraform/provider.tf",
   ".github/terraform/variables.tf":"cloud/blockstore/github_toplevel/.github/terraform/variables.tf",
   ".github/terraform/versions.tf":"cloud/blockstore/github_toplevel/.github/terraform/versions.tf",
+  ".github/workflows/README.md":"cloud/blockstore/github_toplevel/.github/workflows/README.md",
   ".github/workflows/build_and_test_act.yaml":"cloud/blockstore/github_toplevel/.github/workflows/build_and_test_act.yaml",
   ".github/workflows/build_and_test_on_demand.yaml":"cloud/blockstore/github_toplevel/.github/workflows/build_and_test_on_demand.yaml",
   ".github/workflows/build_and_test_ya.yaml":"cloud/blockstore/github_toplevel/.github/workflows/build_and_test_ya.yaml",