ci,README: improve install instructions

.github/workflows/go.yml

@@ -32,10 +32,10 @@ jobs:
       - name: Install LLVM ${{ matrix.llvm }} and libgc-dev
         if: startsWith(matrix.os, 'ubuntu')
         run: |
-          echo 'deb http://apt.llvm.org/focal/ llvm-toolchain-focal-${{ matrix.llvm }} main' | sudo tee /etc/apt/sources.list.d/llvm.list
+          echo "deb http://apt.llvm.org/$(lsb_release -cs)/ llvm-toolchain-$(lsb_release -cs)-${{ matrix.llvm }} main" | sudo tee /etc/apt/sources.list.d/llvm.list
           wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
           sudo apt-get update
-          sudo apt-get install --no-install-recommends clang-${{ matrix.llvm }} llvm-${{ matrix.llvm }}-dev libgc-dev
+          sudo apt-get install -y --no-install-recommends llvm-${{ matrix.llvm }}-dev clang-${{ matrix.llvm }} lld-${{ matrix.llvm }} libgc-dev
           echo /usr/lib/llvm-${{ matrix.llvm }}/bin >> $GITHUB_PATH
     
       - name: Clang information