Add dependencies into proto image to support documentation generation (…

…#133)

This is in support of generating protobuf documentation.

proto/01-protoc-base/checksums.txt

@@ -1,3 +1,4 @@
 f853e691868d0557425ea290bf7ba6384eef2fa9b04c323afab49a770ba9da80  protoc-25.3-linux-x86_64.zip
 b0f50f6a857c3e17f7a83ce90d9f877640381100289fedc4658dc47d69bc7f36  protoc-gen-grpc-java-1.63.1-linux-x86_64.exe
 075ed6163fea314c415f67a4af68d1b6dbddc8fa8be35addf74e4c81812a9148  protobuf-javascript-3.21.2-linux-x86_64.zip
+47cd72b07e6dab3408d686a65d37d3a6ab616da7d8b564b2bd2a2963a72b72fd  protoc-gen-doc_1.5.1_linux_amd64.tar.gz

proto/01-protoc-base/install.sh

@@ -31,12 +31,19 @@ wget -q "https://repo1.maven.org/maven2/io/grpc/protoc-gen-grpc-java/${java_plug
 
 js_ver=3.21.2
 wget -q "https://github.com/protocolbuffers/protobuf-javascript/releases/download/v${js_ver}/protobuf-javascript-${js_ver}-linux-x86_64.zip"
+
+doc_plugin_ver=1.5.1
+wget -q "https://github.com/pseudomuto/protoc-gen-doc/releases/download/v${doc_plugin_ver}/protoc-gen-doc_${doc_plugin_ver}_linux_amd64.tar.gz"
+
 sha256sum --check "${__dir}/checksums.txt"
 
 pbuf_zip=protoc-${pbuf_ver}-linux-x86_64.zip
 unzip "$pbuf_zip" -d /opt/protoc
 rm "$pbuf_zip"
 
+tar -xzf "protoc-gen-doc_${doc_plugin_ver}_linux_amd64.tar.gz" -C /usr/local/bin
+rm "protoc-gen-doc_${doc_plugin_ver}_linux_amd64.tar.gz"
+
 mkdir -p /opt/java/bin
 
 mv "protoc-gen-grpc-java-${java_plugin_ver}-linux-x86_64.exe" /opt/java/bin/protoc-gen-grpc-java