docs: Add docs for IPFS (#143)

docs/go-storage/services/ipfs.md

@@ -1,3 +1,43 @@
+[InterPlanetary File System(IPFS)](https://ipfs.io/)
+
 ## Project
 
-<https://github.com/beyondstorage/go-service-ipfs>
+<https://github.com/beyondstorage/go-service-ipfs>
+
+## Config
+
+### Storager
+
+#### Available Pairs
+
+| Name | Required | Comments |
+| ---- | -------- | -------- |
+| [endpoint](go-storage/pairs/endpoint.md) | Y | endpoint |
+| [work_dir](go-storage/pairs/work_dir.md) | N | work dir |
+
+#### Examples
+
+Init storager (see [this page](go-storage/operations/index.md#how-to-initialize-a-servicerstorager) for details)
+
+```go
+import (
+	_ "github.com/beyondstorage/go-service-ipfs"
+	"github.com/beyondstorage/go-storage/v4/services"
+)
+
+store, err := services.NewStoragerFromString("ipfs:///<work_dir>?endpoint=<ipfs_http_api_endpoint>") // endpoint example: http:127.0.0.1:5001
+if err != nil {
+    log.Fatalf("ipfs new service: %v", err)
+}
+
+```
+
+## Implementation
+
+This service implements following interfaces:
+
+- [Storager](../operations/storager/index.md)
+
+- [Copier](../operations/copy.md)
+
+- [Mover](../operations/move.md)