Change package name & add to Packagist

[mbrodala]

Currently the package name is typo3-ter/guide which is actually only used by composer.typo3.org to provide Composer packages for TER extensions.

The typo3-ter namespace should not be used by anyone outside of that scope.

Thus please change your package name, e.g. to tdeuling/typo3-guide or similar. Please also add it to Packagist while you're at it.

[pixelbrackets]

Also: Please add a git tag for each version. Currently there is a 1.0.0 tag only, but the extension is version 2.0.0 in master.