add go errors

src/Development/Go/errors.md

@@ -0,0 +1,13 @@
+# [errors](https://golang.org/pkg/errors/)
+
+Wrap error:
+
+```go
+err := fmt.Errorf("Something wrong: %w", rootErr)
+```
+
+Unwrap error:
+
+```go
+rootErr := errors.Unwrap(err)
+```

src/SUMMARY.md

@@ -44,6 +44,7 @@
   - [ANTLR](Development/ANTLR/README.md)
     - [Condition](Development/ANTLR/Condition.md)
   - [Go](Development/Go/README.md)
+    - [errors](Development/Go/errors.md)
     - [strings](Development/Go/strings.md)
     - [testing](Development/Go/testing.md)
     - [time](Development/Go/time.md)