Update readme.md (#988)

Update readme.md to be more clearly visually the install comand and easier to copy pasta

README.md

diff --git a/README.md b/README.md
index 04a52df..2e253e6 100644
--- a/README.md
+++ b/README.md
@@ -25,7 +25,10 @@
   for details or, if you are using gccgo, follow the instructions at
 	https://golang.org/doc/install/gccgo
 - Grab the code from the repository and install the `proto` package.
-  The simplest way is to run `go get -u github.com/golang/protobuf/protoc-gen-go`.
+  The simplest way is to run:
+  ```
+  go get -u github.com/golang/protobuf/protoc-gen-go
+  ```
   The compiler plugin, `protoc-gen-go`, will be installed in `$GOPATH/bin`
   unless `$GOBIN` is set. It must be in your `$PATH` for the protocol
   compiler, `protoc`, to find it.