[ADD] sale: How to link terms and conditions to a quotation?

https://docs.google.com/document/d/18pC3C13q_af1XThPIFAs8PUNkFsZUkiob8nutP-85js/edit#

sales/quotation/setup.rst

@@ -7,4 +7,5 @@ Setup
 
    setup/first_quote
    setup/different_addresses
-   setup/optional
+   setup/optional
+   setup/terms_conditions

sales/quotation/setup/terms_conditions.rst

@@ -1,3 +1,80 @@
-===================================================
-How to link my terms and conditions on a quotation?
-===================================================
+================================================
+How to link terms and conditions to a quotation?
+================================================
+
+Overview
+========
+
+Specifying Terms and conditions is essential to ensure the good
+relationships between customer and seller. Every seller has to declare
+all the formal information which includes products and company policy so 
+customer can read all those terms before committing to anything.
+
+Thanks to Odoo you can easily include your default terms and conditions
+on every quotation, sales order and invoice. Moreover you can also
+include specific information regarding any products.
+
+Let's take the following example: Your company sells water bottles to
+restaurants and you would like to add the following standard terms and
+conditions on all your quotations:
+
+-   *Payment is 30 days net upon delivery. Safe storage of the products
+    of MyCompany is necessary in order to ensure their quality,
+    MyCompany will not be held accountable in case of unsafe storage
+    of the products.*
+
+Configuration
+=============
+
+No special configuration is needed to be able to add your terms and
+conditions. It is however necessary to install the invoice application
+to have the possibility of sending out invoices. To do so go into the
+app module and install the invoicing application.
+
+.. image:: media/terms_conditions01.png
+    :align: center
+
+General terms and conditions
+============================
+
+General terms and conditions can be specified in the company data. They
+will then automatically appear on every sales document from the
+quotation to the invoice.
+
+To specify your Terms and Conditions go into 
+:menuselection:`Settings --> General Settings --> Configure your company data`
+(see picture below).
+
+.. image:: media/terms_conditions02.png
+    :align: center
+
+In this new window you will be able to specify our general terms and
+conditions by editing the page and going in the configuration window
+(see picture below).
+
+.. image:: media/terms_conditions03.png
+    :align: center
+
+Information on the product
+==========================
+
+It is also possible to add specific information regarding a product
+on the quotation. To add information regarding the water bottle in your
+quotation, go into :menuselection:`Sales --> Sales --> Products`.
+
+Select or create your waterbottle in the products. Click on your product, then click the edit button
+
+If you go into the notes widget you will have the possibility to
+specify your description necessary for the quotation (see picture
+below).
+
+.. image:: media/terms_conditions04.png
+    :align: center
+
+Quotation and sales terms
+=========================
+
+After saving, your terms and conditions appear on your quotation.
+
+.. image:: media/terms_conditions05.png
+    :align: center