feat: Add mathjax

HepLean/PerturbationTheory/Wick/Algebra.lean

@@ -25,8 +25,12 @@ We will formally define the operator ring, in terms of the fields present in the
 -/
 
 note "
-  <h1>Operator algebra</h1>
-  This is a test note."
+<h2>Operator algebra</h2>
+The operator algebra is a super-algebra over the complex numbers, which acts on
+the Hilbert space of the theory. A super-algebra is an algebra with a Z/2 grading.
+To do pertubation theory in a QFT we need a need some basic properties of the operator algebra,
+$A$.
+  "
 
 namespace Wick
 

HepLean/PerturbationTheory/Wick/Species.lean

@@ -29,7 +29,8 @@ The first bit of data we need is a type of fields `𝓯`. We also need to know w
 are dual to what other fields, for example in a complex scalar theory `φ` is dual to `φ†`.
 We can encode this information in an involution `ξ : 𝓯 → 𝓯`.
 <br><br>
-...
+The second bit of data we need is how the fields interact with each other. In other words,
+a list of interaction vertices `𝓘`, and the type of fields associated to each vertex.
 <br><br>
 This necessary information to do perturbation theory is encoded in a `Wick Species`, which
 we define as: