registration link added

Author: oliviakowalczyk

docs/courses/index.md

@@ -13,7 +13,7 @@ We are delighted to welcome visitors to our SPM courses every May and October. T
 
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-    May 2025, more details will be announced soon. 
+    19th-22nd May 2025, **online**. | [Registration is now open.](https://onlinestore.ucl.ac.uk/conferences-and-events/faculty-of-brain-sciences-c07/ucl-institute-of-neurology-d07/d07-statistical-parametric-mapping-for-megeeg-2025) 
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 - :fontawesome-solid-brain:{ .lg .middle } [__SPM for fMRI & VBM__](./fmri_vbm/index.md)