Add comprehensive documentation with i18n support (EN/BG)

- Add docs/ folder with English (en/) and Bulgarian (bg/) documentation
- Create index.md with language switching and links
- English docs: installation, quickstart, architecture, baraql, storage,
  schema, lsm, btree, vector, graph, fts, columnar, transactions,
  distributed, protocol, udf, api-binary, api-http, api-websocket
- Bulgarian docs: installation, quickstart, architecture, baraql,
  schema, lsm, btree, vector, graph, fts, transactions, distributed
- Update README license to BSD 3-Clause
- Add LICENSE file with BSD 3-Clause text

docs/bg/distributed.md

@@ -0,0 +1,37 @@
+# Разпределена Система
+
+Поддръжка за разпределено внедряване с Raft консенсус, шардиране и репликация.
+
+## Raft Консенсус
+
+```nim
+import barabadb/core/raft
+
+var cluster = newRaftCluster()
+cluster.addNode("node1")
+cluster.addNode("node2")
+cluster.addNode("node3")
+
+let n1 = cluster.nodes["n1"]
+n1.becomeLeader()
+```
+
+## Шардиране
+
+```nim
+import barabadb/core/sharding
+
+var router = newShardRouter(ShardConfig(numShards: 4, replicas: 2))
+router.rebalance(@["node1", "node2", "node3"])
+let shard = router.getShard("user_123")
+```
+
+## Репликация
+
+```nim
+import barabadb/core/replication
+
+var rm = newReplicationManager(rmSync)
+rm.addReplica(newReplica("r1", "10.0.0.1", 5432))
+rm.connectReplica("r1")
+```