fix(doc): add language annotation to code blocks in README

Update the code blocks in the readme to include a language annotation so
rendering engines may apply syntax highlighting.

The goal is to prevent too much logic being crammed on to a single line

Semver: patch

README.md

@@ -8,7 +8,7 @@ This package contains the `eslint` configuration that LogDNA prefers to use acro
 
 We do not use peer dependencies, so make sure that `eslint` is also installed as a dev dependency.
 
-```
+```shell
 npm install eslint-config-logdna eslint --save-dev
 ```
 
@@ -20,7 +20,7 @@ Once the package is installed, there are a few easy steps to get it executing wi
 
 It is best if `eslint` is configured as a script in `package.json` and hooked in as `pre` scripts where necessary.
 
-```
+```javascript
 "scripts": {
   "lint": "eslint .",
   "pretest": "npm run lint"
@@ -33,7 +33,7 @@ Add this configuration section to the `package.json` file of the target project.
 specific to the project that needs linting.  The `ignorePatterns` is only important for directories that may contain `.js`
 files since `eslint` will only lint javascript files by default.
 
-```
+```javascript
 "eslintConfig": {
   "extends": [
     "logdna"