Start explanations on "compiler concepts" (#2701)

Co-authored-by: h-vetinari <h.vetinari@gmx.com>
Co-authored-by: jaimergp <jaimergp@users.noreply.github.com>

Author: 3 people

docs/_sidebar_diataxis.json

@@ -170,9 +170,9 @@
         "label": "Building packages",
         "items": [
           {
-            "type": "link",
+            "type": "doc",
             "label": "Compilation concepts",
-            "href": "#"
+            "id": "maintainer/understanding_conda_forge/compilation-concepts"
           },
           {
             "type": "link",