Update plugins.md (#5829)
Update plugins.md (#5829)

- Added link to toml prettier plugin (alpha version released).
- Changed link and owner of Java plugin as it was moved to the Jhipster org.

prettier/prettier,rattrayalex/prettier,existentialism/prettier,prettier/prettier,prettier/prettier,existentialism/prettier,rattrayalex/prettier,prettier/prettier,existentialism/prettier,existentialism/prettier,rattrayalex/prettier,jlongster/prettier