[time_series_with_matrices] Update editorial suggestions (#464)

* [time_series_with_matrices] Update editorial suggestions

* Fix inconsistencies in the symbols and variable names

* add intersphinx mapping and link example

* fix intersphinx mapping address

* Update lectures/time_series_with_matrices.md

Co-authored-by: Matt McKay <mmcky@users.noreply.github.com>

* Update lectures/time_series_with_matrices.md

Co-authored-by: Matt McKay <mmcky@users.noreply.github.com>

* Update time_series_with_matrices.md

* Update lectures/time_series_with_matrices.md

Co-authored-by: Matt McKay <mmcky@users.noreply.github.com>

---------

Co-authored-by: Humphrey Yang <u6474961@anu.edu.au>
Co-authored-by: mmcky <mamckay@gmail.com>
Co-authored-by: Matt McKay <mmcky@users.noreply.github.com>

lectures/_config.yml

@@ -75,6 +75,9 @@ sphinx:
         colab_url                 : https://colab.research.google.com
         thebe                     : false  # Add a thebe button to pages (requires the repository to run on Binder)
     intersphinx_mapping:
+      intermediate: 
+        - https://python.quantecon.org/
+        - null
       pyprog:
         - https://python-programming.quantecon.org/
         - null

lectures/lln_clt.md

@@ -167,6 +167,7 @@ $$
 
 The next theorem is called Kolmogorov's strong law of large numbers.
 
+(iid-theorem)=
 ````{prf:theorem}
 If $X_1, \ldots, X_n$ are IID and $\mathbb E |X|$ is finite, then