fix: Missing cd in README.MD Running test locally

[SkollRyu]

Description

./script/install-tools
export OSS_IMAGE="opensearchproject/opensearch:2"
docker-compose up -d
docker-compose ps -a
export OPENSEARCH_URL=http://admin:admin@localhost:9200
export TF_LOG=INFO
TF_ACC=1 go test ./... -v -parallel 20 -cover -short

In this original script, we run it when current directory is the root of repo. but it doesn't work for the last line of command go test because the current directory should be in provider/. So I add a line of cd command before the go test command line

Issues Resolved

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[prudhvigodithi]

Thanks @SkollRyu can you also elaborate what does each step do for testing, so this way it would be easy for a new contributor to understand how the testing works.
Example like

Step 1: What its doing, purpose of this step

<command_used>

Step 2: What its doing, purpose of this step

<command_used>

[SkollRyu]

Thanks for your suggestion. @prudhvigodithi I have added line by line explanation.