adjusted main sidebar and course details

qdrant-landing/content/learn/ref-courses-essential.md

@@ -1,11 +0,0 @@
----
-#Delimiter files are used to separate the list of documentation pages into sections.
-type: reference
-reference: /course/essentials
-weight: 210
-sitemapExclude: True
-_build:
-  publishResources: false
-  render: never
-partition: learn
----

qdrant-landing/content/learn/ref-courses-multivector.md

@@ -1,7 +0,0 @@
----
-title: "Multi-Vector Retrieval"
-weight: 230
-type: external-link
-external_url: https://www.deeplearning.ai/short-courses/multi-vector-image-retrieval/
-partition: learn
----