add core notebooks as cards to example gallery (#415)

* add core notebooks as cards to example gallery

* remove note

Author: OriolAbril

examples/gallery.rst

@@ -6,6 +6,48 @@ PyMC Example Gallery
 
    object_index/index
 
+Core notebooks
+--------------
+
+.. grid:: 1 2 3 3
+   :gutter: 4
+
+   .. grid-item-card:: Introductory Overview of PyMC
+      :img-top: https://raw.githubusercontent.com/pymc-devs/brand/main/logos/PyMC_square.svg
+      :link: pymc:pymc_overview
+      :link-type: ref
+      :shadow: none
+
+   .. grid-item-card:: GLM: Linear regression
+      :img-top: https://raw.githubusercontent.com/pymc-devs/brand/main/logos/PyMC_square.svg
+      :link: pymc:GLM_linear
+      :link-type: ref
+      :shadow: none
+
+   .. grid-item-card:: Model Comparison
+      :img-top: https://raw.githubusercontent.com/pymc-devs/brand/main/logos/PyMC_square.svg
+      :link: pymc:model_comparison
+      :link-type: ref
+      :shadow: none
+
+   .. grid-item-card:: Prior and Posterior Predictive Checks
+      :img-top: https://raw.githubusercontent.com/pymc-devs/brand/main/logos/PyMC_square.svg
+      :link: pymc:posterior_predictive
+      :link-type: ref
+      :shadow: none
+
+   .. grid-item-card:: Distribution Dimensionality
+      :img-top: https://raw.githubusercontent.com/pymc-devs/brand/main/logos/PyMC_square.svg
+      :link: pymc:dimensionality
+      :link-type: ref
+      :shadow: none
+
+   .. grid-item-card:: PyMC and Aesara
+      :img-top: https://raw.githubusercontent.com/pymc-devs/brand/main/logos/PyMC_square.svg
+      :link: pymc:pymc_aesara
+      :link-type: ref
+      :shadow: none
+
 (Generalized) Linear and Hierarchical Linear Models
 ---------------------------------------------------
 
@@ -127,4 +169,4 @@ How to
     :glob:
     :reversed:
 
-    howto/*
+    howto/*