DOCS-1386: Undeprecating mc license update (#1387)

Closes #1386 

# Summary

`mc license update` was mistakenly marked as deprecated.

This adds it back to the main reference.

Staged:
http://192.241.195.202:9000/staging/DOCS-1386/linux/reference/minio-mc/mc-license.html

source/reference/minio-mc/mc-license-update.rst

@@ -0,0 +1,74 @@
+=====================
+``mc license update``
+=====================
+
+.. default-domain:: minio
+
+.. contents:: Table of Contents
+   :local:
+   :depth: 1
+
+.. mc:: mc license update
+
+Description
+-----------
+
+.. start-mc-license-update-desc
+
+Use the :mc-cmd:`mc license update` command to replace a license key for a deployment.
+
+.. end-mc-license-update-desc
+
+For deployments registered for |SUBNET|, MinIO automatically checks for and updates the license every month.
+
+Examples
+--------
+
+Update the License Key for a Deployment with Alias ``minio1``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. code-block:: shell
+   :class: copyable
+
+   mc license update minio1 license.key
+
+Syntax
+------
+      
+The command has the following syntax:
+
+.. code-block:: shell
+
+   mc [GLOBALFLAGS] license update                   \
+                            ALIAS                    \
+                            [LICENSE-FILE-WITH-PATH] \
+                            [--airgap]
+
+Parameters
+~~~~~~~~~~
+
+.. mc-cmd:: ALIAS
+   :required:
+
+   The :ref:`alias <alias>` of the MinIO deployment.
+
+.. mc-cmd:: LICENSE-FILE-WITH-PATH
+   :optional:
+
+   The path (relative to the current working directory) and file name of the key to use to update the deployment's license.
+
+   See the :ref:`troubleshooting page <minio-subnet-license-file-download>` for instructions on downloading the license file.
+   
+.. mc-cmd:: --airgap
+   :optional:
+
+   Use in environments without network access to SUBNET (for example, airgapped, firewalled, or similar configuration).
+
+   If the deployment is airgapped, but the local device where you are using the :ref:`minio client <minio-client>` has network access, you do not need to use the ``--airgap`` flag.
+
+Global Flags
+~~~~~~~~~~~~
+
+.. include:: /includes/common-minio-mc.rst
+   :start-after: start-minio-mc-globals
+   :end-before: end-minio-mc-globals

source/reference/minio-mc/mc-license.rst

@@ -44,10 +44,15 @@ Subcommands
           :start-after: start-mc-license-register-desc
           :end-before: end-mc-license-register-desc
 
+   * - :mc:`~mc license update`
+     - .. include:: /reference/minio-mc/mc-license-update.rst
+          :start-after: start-mc-license-update-desc
+          :end-before: end-mc-license-update-desc
 
 .. toctree::
    :titlesonly:
    :hidden:
    
    /reference/minio-mc/mc-license-info
-   /reference/minio-mc/mc-license-register
+   /reference/minio-mc/mc-license-register
+   /reference/minio-mc/mc-license-update