Description

The link to the Gitter chatroom in README.rst and doc/links_names.inc currently points to https://gitter.im/dipy/dipy. While this link redirects to the Matrix interface, it can be confusing for new users as Gitter has been migrated to Matrix.

This issue proposes updating the documentation to explicitly mention Matrix and use the direct Matrix invite link (https://matrix.to/#/#dipy_dipy:gitter.im) to improve clarity and user experience.

Way to reproduce

1. Go to the DIPY README.rst.
2. Click on the Gitter chatroom link.
3. Observe the redirection and potential confusion for users not familiar with the migration.