Git creds is required to pull in private repos

[alok87]

Fixes #68

~/.netrc file present is required to be present in local machine and needs to be mounted in docker run for containers to be able to pull private repos

Only passing GOPRIVATE=org won't work

Usage after this for local:

• Create ~/.netrc file in ur machine with format:

machine github.com
login thockin
password XX

• GOPRIVATE=thockin make build

Usage after this for ci/GitHub action:

• Export GIT_TOKEN in the github action

• Now, this will work from Github Action

GOPRIVATE=thockin make build

Showing sample usage. Based on discussion will fix the PR.

Would like to take #71 first and then update this PR and take it.