Added FAQ section in readme.md (#460)

* Added FAQ section in readme.md

* Updated readme.

* Moved support to end

* Highlighted FAQ question.

README.md

@@ -4,6 +4,28 @@ This extension utilizes Razorpay API and provides seamless integration with Mage
 
 ### Installation
 
+## **Install through the "code.zip" file**
+### `bin/magento` is executable command, this is to be executed from Magento installation directory.
+
+1. Extract the attached code.zip
+2. Go to the "app" folder
+3. Overwrite content of the "code" folder with step one "code" folder (Note: if the code folder does not exist just place the code folder from step 1).
+4. Run following command to enable Razorpay Magento module: 
+```
+bin/magento module:enable Razorpay_Magento
+```
+5. Run following command to install Magento cron jobs : 
+```
+bin/magento cron:install
+```
+6. Run `bin/magento setup:di:compile` to compile dependency code. 
+7. Run `bin/magento setup:upgrade` to upgrade the Razorpay Magento module from the Magento installation folder.
+8. On the Magento admin dashboard, open Razorpay payment method settings and click on the Save Config button.
+**Note**: If you see this message highlighted in yellow (One or more of the Cache Types are invalidated: Page Cache. Please go to Cache Management and refresh cache types.) on top of the Admin page, please follow the steps mentioned and refresh the cache.
+9. Run `bin/magento cache:flush` once again.
+
+### **OR**
+
 Install the extension through composer package manager.
 
 ```
@@ -16,6 +38,12 @@ You can check if the module has been installed using `bin/magento module:status`
 
 You should be able to see `Razorpay_Magento` in the module list
 
+#### Execute following commands from Magento installation directory:
+```
+bin/magento setup:di:compile
+bin/magento setup:upgrade
+bin/magento cache:flush
+```
 
 Go to `Admin -> Stores -> Configuration -> Payment Method -> Razorpay` to configure Razorpay
 
@@ -117,6 +145,77 @@ mutation {
   }
 }
 ```
+
+## **Upgrade Razorpay plugin through composer**
+If you are an existing user, you can upgrade the Magento extension using the composer. Enter the command given below:
+```
+composer update razorpay/magento
+bin/magento setup:upgrade
+```
+
+## Using  Custom Order Status in Razorpay Magento
+### Step 1: Create Custom Order Status
+- On the Magento Admin Dashboard, Stores > Settings > Order Status.
+- In the upper-right corner, click on Create New Status.
+- Under Order Status Information section, Insert a Status Code for the internal reference. This field required to contain letters (a-z), the number (0-9) and the underscore, it is required to use letters at first character and the rest can be a combination of letters and numbers.
+- Set the Status Label for Admin and storefront.
+- Set the Store View specific labels for each store view on your store.
+- Save status to complete.
+
+### Step 2: Un-assign existing status
+- Un-assign existing status code which is in use. 
+   - If State Code and Title is `processing[Processing]`, then `processing` status is already in use for state `processing`.
+   - Un-assign this status from existing state code `processing`, so that state will be available for your custom status code.
+
+### Step 3: Assign an order status to a state
+- Go to the Order Status page, click on Assign Status to State button.
+- In the Assign Order Status to State section,
+   - From the existing list of the order status, select the Order Status to assign.
+   - Choose the Order State to include the order status you’ve just assigned. **Use Order state as `processing`**
+    - Accept the order status as a default status, tick the Use Order Status as Default checkbox.
+    - Enable the order status on the storefront, please tick the Visible On Storefront checkbox.
+ - Click on ` Save Status Assignment` to complete.
+
+### Step 4: Using Custom order status for Razorpay Magento
+- On the Magento admin dashboard, open Razorpay payment method settings.
+- At field `Custom Paid Order Status` select `Yes` to enable custom order status, select `No` to disable custom order status.
+-  Insert Custom Paid Order Status value at input field provided with same value which has been used as Status Code while creating custom status.
+- Save configuration & refresh the cache.
+
+## Uninstall OR Rollback to older versions
+To rollback, you will be required to uninstall existing version and install a new version again. Following are actions used for rollback & reinstall:
+
+### Uninstall Razorpay Magento
+**If composer is used for installation, use following commands from Magento installation directory to uninstall Razorpay Magento module** 
+```
+php bin/magento module:disable Razorpay_Magento
+php bin/magento module:uninstall Razorpay_Magento
+```
+
+**If code.zip is used for installation, to uninstall following steps can be used:**
+Disabled Razorpay Magento module
+```
+php bin/magento module:disable Razorpay_Magento
+```
+
+To remove module directory, execute following command from Magento install directory
+```
+rm -rf app/code/Razorapy
+```
+
+Remove module schema from MYSQL database
+```
+DELETE FROM `setup_module` WHERE `setup_module`.`module` = 'Razorpay_Magento';
+```
+
+### Re-Install Razorpay Magento
+To install Razorpay Magento module, follow installation steps provided at this release document. Following are previously released versions [3.7.5](https://github.com/razorpay/razorpay-magento/releases/tag/3.7.5) and [4.0.4](https://github.com/razorpay/razorpay-magento/releases/tag/4.0.5).
+
+### FAQ
+
+## How to upgrade plugin using code.zip?
+Download the latest code.zip and replace all the contents of the code folder with the new code.zip content. Then follow the same steps which are there for installation through code.zip.
+
 ### Support
 
 Visit [https://razorpay.com](https://razorpay.com) for support requests or email [email protected].