docs: add readmes for each of the projects

.dockerignore

.env.example

OCM Gateway.postman_collection.json

README.md

apps/agent/README.md

apps/agent/deployment/Dockerfile

apps/agent/src/app/app.module.ts

apps/attestation-manager/README.md

apps/connection-manager/README.md

apps/gateway/README.md

apps/gateway/src/app/managers/attestation.controller.ts

apps/gateway/src/app/managers/connection.controller.ts

apps/gateway/src/app/managers/proof.controller.ts

apps/gateway/src/main.ts

apps/proof-manager/README.md

compose/docker-compose.yml

compose/env/holder.env

compose/env/issuer.env

gateway-swagger.json

libs/askar/.eslintrc.json