Fix link to download crd-ref-docs

This workflow has been failing for a while because the binary we downloaded is no longer available. This PR updates the workflow to download an available file.

Author: JakeSCahill

.github/workflows/generate-crd.yml

@@ -39,7 +39,8 @@ jobs:
       # Download crd-ref-docs utility for doc generation.
       - name: Download crd-ref-docs
         run: |
-          curl -fLO https://github.com/elastic/crd-ref-docs/releases/download/v0.1.0/crd-ref-docs
+          curl -fLO https://github.com/elastic/crd-ref-docs/releases/download/v0.1.0/crd-ref-docs_0.1.0_Linux_x86_64.tar.gz
+          tar -xzf crd-ref-docs_0.1.0_Linux_x86_64.tar.gz
           chmod +x crd-ref-docs
           sudo mv crd-ref-docs /usr/local/bin/
       # Generate Operator CRD documentation.