docs: fix Ubuntu 20.04 installation guide (#270)

Author: SnehaChaursia

Doc/install-certifier-Ubuntu-20.04.md

@@ -1,97 +1,118 @@
 # Install Certifier (Ubuntu 20.04)
 
-
 ### Setup Environment variables 
 
+```bash
 cd ~/Projects
 git clone https://github.com/ccc-certifier-framework/certifier-framework-for-confidential-computing.git
 
 export CERTIFIER=~/Projects/certifier-framework-for-confidential-computing
 export EXAMPLE_DIR=$CERTIFIER/sample_app
+```
 
 ### Install Dependencies
-```
-sudo apt install libgtest-dev libgflags-dev
+
+**Note**: The UUID library is required for compilation but was missing from the original documentation.
+
+```bash
+sudo apt update
+sudo apt install libgtest-dev libgflags-dev uuid-dev
 ```
 
 We note that the versioning of `protobuf` and `golang` matters. One shall not use the distribution directly `apt`-ed from Ubuntu. 
 
 Install the latest protobuf from source by 
-```
+```bash
 sudo apt install autoconf automake libtool curl make g++ unzip
 git clone https://github.com/protocolbuffers/protobuf.git
 cd protobuf
 git submodule update --init --recursive
 ./autogen.sh && ./configure
- make -j$(nproc)  &&  sudo make install
- sudo ldconfig # refresh shared library cache.
+make -j$(nproc) && sudo make install
+sudo ldconfig # refresh shared library cache.
 ``` 
-the detailed installation procedure can be found https://github.com/protocolbuffers/protobuf/blob/main/src/README.md. 
+The detailed installation procedure can be found https://github.com/protocolbuffers/protobuf/blob/main/src/README.md. 
 
 Install the latest `golang` by  
-```
+```bash
 sudo apt install wget 
 wget https://go.dev/dl/go1.18.4.linux-amd64.tar.gz
 sudo rm -rf /usr/local/go && sudo tar -C /usr/local -xzf go1.18.4.linux-amd64.tar.gz
 export PATH=$PATH:/usr/local/go/bin && export PATH=$PATH:$(go env GOPATH)/bin
 rm go1.18.4.linux-amd64.tar.gz
 ```
 
-The protobuf compiler(protoc) for golang is installed by 
+**Updated Go Protobuf Installation**: The `go get` commands are deprecated. Use `go install` instead:
+```bash
+go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
+go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest
 ```
-go get github.com/golang/protobuf/proto
-go get google.golang.org/protobuf/cmd/protoc-gen-go
+
+**Alternative method** (if the above doesn't work, as referenced in the grpc.io quickstart):
+```bash
+go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.28
+go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@v1.2
 ```
 
 Ensure OpenSSL library and OpenSSL headers are installed or install by
-```
-sudo apt install openssl
-sudo apt install libssl-dev
+```bash
+sudo apt install openssl libssl-dev
 ```
 Current tests on Ubuntu are with OpenSSL 1.1.1f.
 
 ### Compile Certifier Library 
+
 The certifier library can be compiled by 
-```
- cd $CERTIFIER/src
- make -f certifier.mak
+```bash
+cd $CERTIFIER/src
+make -f certifier.mak
 
 cd $CERTIFIER/utilities
 make -f cert_utility.mak
 make -f policy_utilities.mak
 ```
 
-
 ### Build the Certifier Service 
 
 1. Compile the protobuf required by certifier service by 
-```
- cd $CERTIFIER/certifier_service/certprotos
- protoc --go_opt=paths=source_relative --go_out=. --go_opt=Mcertifier.proto= ./certifier.proto
+```bash
+cd $CERTIFIER/certifier_service/certprotos
+protoc --go_opt=paths=source_relative --go_out=. --go_opt=Mcertifier.proto= ./certifier.proto
 ```
 
 2. Install the certifier as go library by
-```
-go install  github.com/jlmucb/crypto@latest
+```bash
+go install github.com/jlmucb/crypto@latest
 # TODO: this is a workaround to an existing path issue 
 mkdir -p $(go env GOPATH)/src/github.com/jlmucb/crypto/v2
 sudo cp -r $CERTIFIER $(go env GOPATH)/src/github.com/jlmucb/crypto/v2
 ```
 
 3. Build the simple server
-```
- cd $CERTIFIER/certifier_service
- go build simpleserver.go
+```bash
+cd $CERTIFIER/certifier_service
+go build simpleserver.go
 ```
 If showing error of `go.mod not found`, run `go env -w GO111MODULE=off` before building. 
 
-
 ### Run `sample_app`
 
 To run sample application, follow the README in sample_app or directly run 
-```
+```bash
 cd $EXAMPLE_DIR
 chmod +x ./script
 ./script
 ```
 
+## Troubleshooting
+
+### Common Issues:
+
+1. **UUID library missing**: If you get `fatal error: uuid/uuid.h: No such file or directory`, ensure you've installed `uuid-dev`:
+   ```bash
+   sudo apt install uuid-dev
+   ```
+
+2. **Go protobuf installation issues**: The original `go get` commands are deprecated. Use the updated `go install` commands provided above, or refer to the official gRPC Go quickstart guide at https://grpc.io/docs/languages/go/quickstart/
+
+3. **Protobuf version conflicts**: Make sure to install protobuf from source rather than using the Ubuntu package to avoid version mismatches.