Updated Day 2 notebooks, including instructor version and blank copy; updated TOC and index page

Author: ethan-campbell

site/_toc.yml

@@ -14,7 +14,7 @@ parts:
     title: Overview
   - file: "lessons/APL_SURP_Python_course_Notebook_1.ipynb"
     title: Day 1
-  - file: "lessons/APL_SURP_Python_course_Notebook_2_blank_copy.ipynb"
+  - file: "lessons/APL_SURP_Python_course_Notebook_2.ipynb"
     title: Day 2
 - caption: Other resources
   chapters:

site/lessons/APL_SURP_Python_course_Notebook_2.ipynb

@@ -4,14 +4,20 @@
   <img src="https://colab.research.google.com/assets/colab-badge.svg" alt="Open In Colab"/>
 </a>
 
-   * To open a blank notebook copy: <a target="_blank" href="https://colab.research.google.com/github/UW-APL-SURP/aplsurp-python/blob/main/site/lessons/APL_SURP_Python_course_Notebook_1_blank_copy.ipynb">
+   * To open a blank copy: <a target="_blank" href="https://colab.research.google.com/github/UW-APL-SURP/aplsurp-python/blob/main/site/lessons/APL_SURP_Python_course_Notebook_1_blank_copy.ipynb">
   <img src="https://colab.research.google.com/assets/colab-badge.svg" alt="Open In Colab"/>
 </a>
 
-2. [Day 2](APL_SURP_Python_course_Notebook_2_blank_copy.ipynb): 2-D arrays, tabular data, plotting, and more <a target="_blank" href="https://colab.research.google.com/github/UW-APL-SURP/aplsurp-python/blob/main/site/lessons/APL_SURP_Python_course_Notebook_2_blank_copy.ipynb">
+2. [Day 2](APL_SURP_Python_course_Notebook_2.ipynb): 2-D arrays, tabular data, datetimes, and more <a target="_blank" href="https://colab.research.google.com/github/UW-APL-SURP/aplsurp-python/blob/main/site/lessons/APL_SURP_Python_course_Notebook_2.ipynb">
   <img src="https://colab.research.google.com/assets/colab-badge.svg" alt="Open In Colab"/>
 </a>
 
+   * To open a blank copy: <a target="_blank" href="https://colab.research.google.com/github/UW-APL-SURP/aplsurp-python/blob/main/site/lessons/APL_SURP_Python_course_Notebook_2_blank_copy.ipynb">
+  <img src="https://colab.research.google.com/assets/colab-badge.svg" alt="Open In Colab"/>
+</a>
+
+3. Day 3: Coming soon
+
 More lessons will be added to this page throughout the summer.
 
 To learn about Python topics in more detail, see the external lessons we've curated in the [Complementary lesssons page](../complementary_lessons) and the [Advanced examples page](../advancedexamples).