Update cAddSub docs to align equations (#1827)

It seems like this was meant to be on two separate lines, but the
currently rendered output is on one line.

This ultimately affected the rendering at
[qualtran.dev](https://qualtran.dev/explore/ControlledAddOrSubtract).

Before the change:
<img width="700" height="300" alt="before"
src="https://github.com/user-attachments/assets/dfe4eef5-2777-41b8-8dea-9076f8bf6b76"
/>

After the change:
<img width="600" height="400" alt="after"
src="https://github.com/user-attachments/assets/412a81ff-7b4f-4908-b3f6-6edfac08299f"
/>

---------

Co-authored-by: Matthew Harrigan <mpharrigan@google.com>

Author: KLee1248

qualtran/bloqs/arithmetic/controlled_add_or_subtract.ipynb

@@ -41,8 +41,10 @@
     "Applies the transformation\n",
     "\n",
     "$$\n",
+    "\\begin{aligned}\n",
     "    |1\\rangle |a\\rangle |b\\rangle \\mapsto |1\\rangle |a\\rangle |b + a\\rangle \\\\\n",
     "    |0\\rangle |a\\rangle |b\\rangle \\mapsto |0\\rangle |a\\rangle |b - a\\rangle\n",
+    "\\end{aligned}\n",
     "$$\n",
     "\n",
     "Given two numbers `a`, `b` and a control bit `ctrl`, this bloq computes:\n",

qualtran/bloqs/arithmetic/controlled_add_or_subtract.py

@@ -32,8 +32,10 @@ class ControlledAddOrSubtract(Bloq):
     Applies the transformation
 
     $$
+    \begin{aligned}
         |1\rangle |a\rangle |b\rangle \mapsto |1\rangle |a\rangle |b + a\rangle \\
         |0\rangle |a\rangle |b\rangle \mapsto |0\rangle |a\rangle |b - a\rangle
+    \end{aligned}
     $$
 
     Given two numbers `a`, `b` and a control bit `ctrl`, this bloq computes: