[Feedback] IAM policy for Read-only users

**Page**: under `/cli/teams`

**Feedback**:

IAM policy for read-only users, who are able to execute `amplify init`, `amplify mock` and `amplify add`, would be super helpful for front-end developers. In the section "cli/teams", describes how full-stack developers manage multiple env, but front-end developer should be prohibited to execute `amplify push` from local env in most cases.

BTW, IAM policy generated by IAM Access Analyzer should be like below

```json
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": "amplify:ListApps",
"Resource": "*"
},
{
"Effect": "Allow",
"Action": [
"amplify:CreateBackendEnvironment",
"amplify:GetApp",
"amplify:GetBackendEnvironment",
"amplify:ListBackendEnvironments"
],
"Resource": "*"
},
{
"Effect": "Allow",
"Action": "s3:CreateBucket",
"Resource": "arn:aws:s3:::*"
}
]
}
```