Update readme, package, gitignore

Author: LucaScorpion

.gitignore

@@ -2,7 +2,7 @@
 node_modules/
 
 # Build output
-./darcula.css
+/darcula.css
 
 # JetBrains
 .idea/

README.md

@@ -23,7 +23,7 @@ This theme can be used in Gatsby with [gatsby-remark-prismjs]. Simply install th
 npm install prismjs-darcula-theme
 ```
 
-Add this line in `gatsby-browser.js`:
+And add this line in `gatsby-browser.js`:
 
 ```js
 import 'prismjs-darcula-theme/darcula.css';

package.json

@@ -17,7 +17,8 @@
     "css",
     "scss",
     "style",
-    "dark"
+    "dark",
+    "gatsby"
   ],
   "author": "@LucaScorpion",
   "repository": "github:LucaScorpion/prismjs-darcula-theme",