adjust readme

README.md

 # Prepation
 
-``npm init``
+```
+npm init
+```
 
 See More <https://graphql-code-generator.com/docs/getting-started/installation>
 
-``npm add --save graphql``
+```
+npm add --save graphql
+```
 or
-``yarn add graphql``
+```
+yarn add graphql
+```
 
 
-``npm add --save-dev @graphql-codegen/cli``
+```
+npm add --save-dev @graphql-codegen/cli
+```
 or
-``yarn add -D @graphql-codegen/cli``
+```
+yarn add -D @graphql-codegen/cli
+```
 
 
-``npx graphql-codegen init``
+```
+npx graphql-codegen init
+```
 
 
-``npm add --save-dev @graphql-codegen/typescript``
+```
+npm add --save-dev @graphql-codegen/typescript
+```
 or
-``yarn add -D @graphql-codegen/typescript``
+```
+yarn add -D @graphql-codegen/typescript
+```
 
 # Server
 
-``npm add apollo-server``
+```
+npm add apollo-server
+```
 
-``npm install @types/node --save-dev``
+```
+npm install @types/node --save-dev
+```
 
 ```
 npx tsc --init --rootDir src --outDir build \
 --module commonjs --allowJs true --noImplicitAny true
 ```
 
-``npm install --save-dev ts-node nodemon rimraf``
+```
+npm install --save-dev ts-node nodemon rimraf
+```
 
 
 # UI
 
-* init new Angular project ``ng new graphql-demo``
+* init new Angular project 
+```
+ng new graphql-demo
+```