go-fmt: add page (#6703)

pages/common/go-fmt.md

@@ -0,0 +1,25 @@
+# go fmt
+
+> Format Go source files.
+> Prints the filenames that are changed.
+> More information: <https://pkg.go.dev/cmd/go#hdr-Gofmt__reformat__package_sources>.
+
+- Format Go source files in the current directory:
+
+`go fmt`
+
+- Format a specific Go package in your import path (`$GOPATH/src`):
+
+`go fmt {{path/to/package}}`
+
+- Format the package in the current directory and all subdirectories (note the `...`):
+
+`go fmt {{./...}}`
+
+- Print what format commands would've been run, without modifying anything:
+
+`go fmt -n`
+
+- Print which format commands are run as they are run:
+
+`go fmt -x`