Update readme.

Author: pmatseykanets

README.md

@@ -54,7 +54,124 @@ Specify the database connection that should be used to access indexed documents
 
 ## Configuration
 
-TBD
+### Configuring PostgreSQL
+
+Make sure that an appropriate [default text search configuration](https://www.postgresql.org/docs/9.5/static/runtime-config-client.html#GUC-DEFAULT-TEXT-SEARCH-CONFIG) is set globbaly (in `postgresql.conf`), for a particular database (`ALTER DATABASE ... SET ...`) or alternatively set `default_text_search_config` in each session.
+
+To check the current value
+
+```sql
+SHOW default_text_search_config;
+
+```
+
+
+
+
+### Prepare the schema
+
+By default the engine expects that parsed documents (model data) are stored in the same table as the Model in a column `searchable` of type `tsvector`. You'd need to create this column and an index in your schema. You can choose between `GIN` and `GiST` indexes in PostgreSQL.
+
+```php
+class CreatePostsTable extends Migration
+{
+    public function up()
+    {
+        Schema::create('posts', function (Blueprint $table) {
+            $table->increments('id');
+            $table->text('title');
+            $table->text('content')->nullable();
+            $table->integer('user_id');
+            $table->timestamps();
+        });
+    
+        DB::statement('ALTER TABLE posts ADD searchable tsvector NULL');
+        DB::statement('CREATE INDEX posts_searchable_index ON posts USING GIN (searchable)');
+        // Or alternatively
+        // DB::statement('CREATE INDEX posts_searchable_index ON posts USING GIST (searchable)');
+    }
+    
+    public function down()
+    {
+        Schema::drop('posts');
+    }
+}
+```
+
+### Configuring Searchable Data
+
+In addition to Model's attributes you can bring other any other data to the index document. I.e. a list of Tags for a Post.
+
+```php
+public function toSearchableArray()
+{
+    return [
+        'title' => $this->title,
+        'content' => $this->content,
+        'author' => $this->user->name,
+        'tags' => $this->tags->pluck('tag')->implode(' '),
+    ];
+}
+
+```
+
+### Configuring the Model
+
+You may fine tune the engine behavior for a particular Model by implemeting `searchableOptions()` in your Model.
+
+```php
+class Post extends Model
+{
+    use Searchable;
+
+	...
+    public function searchableOptions()
+    {
+        return [
+            // You may wish to change the default name of the column
+            // that holds parsed documents
+            'column' => 'indexable',
+            // You may want to store the index outside of the Model table
+            // In that case let the engine know by setting this parameter to true.
+            'external' => true,
+            // If you don't want scout to maintain the index for you
+            // You can turn it off either for a Model or globally
+            'maintain_index' => true,
+            // Ranking groups that will be assigned to fields
+            // when document is being parsed.
+            // Available groups: A, B, C and D.
+            'rank' => [
+                'fields' => [
+                    'title' => 'A',
+                    'content' => 'B',
+                    'author' => 'D',
+                    'tags' => 'C',
+                ],
+                // Ranking weights for searches.
+                // [D-weight, C-weight, B-weight, A-weight].
+                // Default [0.1, 0.2, 0.4, 1.0].
+                'weights' => [0.1, 0.2, 0.4, 1.0],
+                // Ranking function [ts_rank | ts_rank_cd]. Default ts_rank.
+                'function' => 'ts_rank_cd',
+                // Normalization index. Default 0.
+                'normalization' => 32,
+            ],
+        ];
+    }
+}
+...
+```
+
+If you decide to keep your Model's index outside of the Model's table you can let engine know that you want to push additional fields in the index table that you can than use to filter the result set by using `where()` with the Scout `Builder`. In this case you'd need to implement `searchableAdditionalArray()` on your Model. Of course the schema for the external table should include these additional columns.
+
+```php
+public function searchableAdditionalArray()
+{
+    return [
+        'user_id' => $this->user_id,
+    ];
+}
+```
 
 ## Usage