Align documentation after repository rename and v0.1.0 release

[withoutspam]

Summary

This documentation-only follow-up aligns the repository contents with the rename to esphome-opendtu-meter-bridge and the published v0.1.0 release.

It:

• replaces the remaining references to the old repository URL in the README badges and examples, issue template, and NOTICE;
• identifies v0.1.0 as the release that introduced the meter-neutral component name;
• updates the current 0.1.x migration examples while preserving the existing compatibility commitment through 0.2.x and removal no earlier than v0.3.0;
• moves the already released changes from Unreleased to a dated v0.1.0 changelog entry while retaining an empty Unreleased section;
• updates the release guidance to recommend pinning @v0.1.0 for production installations.

These inconsistencies resulted from merging #2, renaming the repository, and publishing v0.1.0 in quick succession. There are no runtime or configuration-schema changes in this PR. Existing old URLs continue to work through GitHub redirects.

Repository-side note

There is also a v.0.1.0 tag alongside the canonical v0.1.0 tag. Both currently point to the same commit. This PR does not modify tags, but the extra tag may be worth removing if it was created accidentally.

Validation

• git diff --check
• verified that no references to Lewa-Reka/esphome-opendtu-to-sdm630 remain in tracked files

[Lewa-Reka]

@withoutspam thx;)