Update Mission210Solution.ipynb

Adjusted headers (as per [this](https://app.asana.com/0/1109607871564464/1185434324869548/f) ticket).

Mission210Solution.ipynb

@@ -610,7 +610,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Answer terms in the question\n",
+    "## Recycled questions\n",
     "\n",
     "The answer only appears in the question about `6%` of the time.  This isn't a huge number, and means that we probably can't just hope that hearing a question will enable us to figure out the answer.  We'll probably have to study."
    ]
@@ -658,7 +658,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Question overlap\n",
+    "## Low value vs high value questions\n",
     "\n",
     "There is about `70%` overlap between terms in new questions and terms in old questions.  This only looks at a small set of questions, and it doesn't look at phrases, it looks at single terms.  This makes it relatively insignificant, but it does mean that it's worth looking more into the recycling of questions."
    ]