added documentation on how to create a search

docs/how_to_create_search.md

 # How to create a search
 
-- [How to create a search](#how-to-create-a-search)
-  * [Create the data processor](#create-the-data-processor)
-  * [Add the data sources](#add-the-data-sources)
-    + [Add a data source for the household member](#add-a-data-source-for-the-household-member)
-    + [Add a data source for the e-mail address of the household member](#add-a-data-source-for-the-e-mail-address-of-the-household-member)
-    + [Add the Relationship data source](#add-the-relationship-data-source)
-    + [Add the Household data source](#add-the-household-data-source)
-    + [Add the address data source](#add-the-address-data-source)
-  * [Add the fields](#add-the-fields)
-  * [Add the exposed filters](#add-the-exposed-filters)
-  * [Add the Contact Search Output.](#add-the-contact-search-output)
-    + [Add the contact search output](#add-the-contact-search-output)
-    + [Add the CSV Export output](#add-the-csv-export-output)
-  * [Start using the search](#start-using-the-search)
+- [Create the data processor](#create-the-data-processor)
+- [Add the data sources](#add-the-data-sources)
+  * [Add a data source for the household member](#add-a-data-source-for-the-household-member)
+  * [Add a data source for the e-mail address of the household member](#add-a-data-source-for-the-e-mail-address-of-the-household-member)
+  * [Add the Relationship data source](#add-the-relationship-data-source)
+  * [Add the Household data source](#add-the-household-data-source)
+  * [Add the address data source](#add-the-address-data-source)
+- [Add the fields](#add-the-fields)
+- [Add the exposed filters](#add-the-exposed-filters)
+- [Add the Contact Search Output.](#add-the-contact-search-output)
+  * [Add the contact search output](#add-the-contact-search-output)
+  * [Add the CSV Export output](#add-the-csv-export-output)
+- [Start using the search](#start-using-the-search)
 
 In this tutorial we are going to create a search action. We search all people who have an active relationship with a household.
 We will show the name, e-mailaddress of the person and we will show the name and address of the household.