Add MultiSumm section to 2026 edition

Added a new section on MultiSumm for multimodal summarization of food sharing initiatives.

Author: cmihaigabriel

_editions/2026.md

@@ -37,6 +37,10 @@ Medico 2026 focuses on Visual Question Answering (VQA) for gastrointestinal (GI)
 
 The goal of this task is to study the long-term memory performance when recognising small movie excerpts or commercial videos. We provide the videos, precomputed features or EEG features for the challenges proposed in the task such as how memorable a video, if a person is familiar with a video or if you can predict the brand memorability?
 
+##### MultiSumm: Multimodal summarization of multiple topically related websites
+
+Participants are provided with links to multimodal web content from several cities listing food sharing initiatives (FSIs) in each city. For each city, participants are tasked with creating a multimodal summary of the FSI activities in the city that satisfy specified criteria. Evaluation will explore the use of emerging LLMs-based methods in automated assessment of multimodal multi-document summarization.
+
 ##### NewsImages at MediaEval 2026 Retrieval and Generative AI for News Thumbnails
 
 Participants receive a large set of articles (including the headline and article lead) in the English-language from international publishers. We offer two subtasks: retrieving an image for each article from a collection of images that can serve as a thumbnail, or generating an article thumbnail.