adds migration information and VkDropin info.

docs/source/how_to/upgrading_1_0_1_to_1_1_0.md

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+# Upgrading from v1.0.1
+
+```{note} This how-to is only relevant for people who used Auto Archiver before June 2025 (versions prior to 1.0.1).
+
+If you are new to Auto Archiver, then you are already using the latest configuration format and this how-to is not relevant for you.
+```
+
+Versions 1.1.0+ of Auto Archiver has breaking changes in the configuration format, which means earlier configuration formats will not work without slight modifications.
+
+
+## Dropping `vk_extractor` module
+We have dropped the `vk_extractor` because of problems in a project we relied on. You will need to remove it from your configuration file, otherwise you will see an error like:
+
+```{code} console
+Module 'vk_extractor' not found. Are you sure it's installed/exists?
+```
+
+## New `antibot_extractor_enricher` module
+We have added a new `antibot_extractor_enricher` module that uses a computer-controlled browser to extract content from websites that use anti-bot measures. You can add it to your configuration file like this:
+
+```{code} yaml
+steps:
+  extractor_enrichers:
+	- antibot_extractor_enricher
+```
+
+It comes with Dropins that we will be adding and maintaining. 
+
+> Dropin: A module that is loaded automatically. You don't need to add them to your configuration steps for them to run. Sometimes they need `authentication` configurations though.
+
+One such Dropin is the VkDropin which uses this automated browser to access VKontakte (VK) pages. You should add a username/password to the configuration file if you get authentication blocks from VK, to do so use the [authentication settings](authentication_how_to.md):
+
+```{code} yaml
+authentication:
+  vk:
+	username: your_username
+	password: your_password
+```
+
+See all available Dropins in [the source code](https://github.com/bellingcat/auto-archiver/tree/main/src/auto_archiver/modules/antibot_extractor_enricher/dropins). Usually each Dropin needs its own authentication settings, similarly to the VkDropin.