Rewrite README around the community fork story:
- state Gitmost is an AGPL-only fork of Docmost with NO Enterprise-Edition
code (ee dirs removed) and replacements written from scratch
- add a "What's different from Docmost" table (EE removal, comment
resolution, embedded MCP, rebranding, compact tree, GHCR CI)
- reframe the MCP section: it is our own docmost-mcp built in, better than
Docmost's coarse EE MCP (agent-native tools), and the same server as the
standalone one — just bundled (Docmost + docmost-mcp in one package)
- group the roadmap into Done / In progress / Planned; done: MCP, macOS
app; in progress: AI chat, git sync; planned: templates, viewer
comments, password-protected pages, Windows/Linux app, mobile app,
offline/PWA, and a batch of editor & UX improvements
- update the License section to reflect the absence of EE directories
- add README.ru.md (full Russian translation) and an English/Russian
language switcher to both files
