[improvement] Declare Versining Rule in README.md

## Subject

Declare Versining Rule in README.md in all animagram repos.

For Semantic Versioning Repos:
```
This project adheres to [Semantic Versioning](https://semver.org/).
```

For Calendar Versioning Repos:
```
This project uses [Calendar Versioning](https://calver.org/) with the 
scheme `YYYY.0M.MICRO` (full year, zero-padded month, and a sequential 
micro version within each month).
```
