Core User Guide Feeedback Implemented.

Feedback Issues left:

1.Issues with red-agent image not embeded correctly in data_manipulation_e2e notebook

2._autosummary/tests.unit_tests.html is still completely blank.

3. _index.html is not updated with new 2-pager

4. _dependencies is not updated to just include tier-1 and primary for v3.

5. definiton of user_app_home is not confirmed

src/primaite/notebooks/multi-processing.ipynb

@@ -4,8 +4,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Simple multi-processing demo using SubprocVecEnv from SB3\n",
-    "Based on a code example provided by Rachael Proctor."
+    "## Simple multi-processing demo using SubprocVecEnv from SB3"
    ]
   },
   {