fix(docs): Fix heading level

Author: Airblader

projects/ngqp-demo/src/app/docs-items/model-usage/model-usage-docs.component.html

@@ -12,25 +12,25 @@ <h2>QueryParamGroup</h2>
         <!-- TODO -->
     </p>
     <docs-fragment fragment="QueryParamGroup-get">
-        <h2>Access individual parameters</h2>
+        <h3>Access individual parameters</h3>
     </docs-fragment>
     <p>
         <!-- TODO -->
     </p>
     <docs-fragment fragment="QueryParamGroup-value">
-        <h2>Reading the current value</h2>
+        <h3>Reading the current value</h3>
     </docs-fragment>
     <p>
         <!-- TODO -->
     </p>
     <docs-fragment fragment="QueryParamGroup-valueChanges">
-        <h2>Subscribing to value changes</h2>
+        <h3>Subscribing to value changes</h3>
     </docs-fragment>
     <p>
         <!-- TODO -->
     </p>
     <docs-fragment fragment="QueryParamGroup-patchValue-setValue">
-        <h2>Updating the values</h2>
+        <h3>Updating the values</h3>
     </docs-fragment>
     <p>
         <!-- TODO -->
@@ -43,21 +43,21 @@ <h2>QueryParam</h2>
         <!-- TODO -->
     </p>
     <docs-fragment fragment="QueryParam-value">
-        <h2>Reading the current value</h2>
+        <h3>Reading the current value</h3>
     </docs-fragment>
     <p>
         This is analogous to <docs-link fragment="QueryParamGroup-value">QueryParamGroup</docs-link>. You can find
         the API documentation under <span apiDocsLink>QueryParam#value</span>.
     </p>
     <docs-fragment fragment="QueryParam-valueChanges">
-        <h2>Subscribing to value changes</h2>
+        <h3>Subscribing to value changes</h3>
     </docs-fragment>
     <p>
         This is analogous to <docs-link fragment="QueryParamGroup-valueChanges">QueryParamGroup</docs-link>. You can find
         the API documentation under <span apiDocsLink>QueryParam#valueChanges</span>.
     </p>
     <docs-fragment fragment="QueryParam-setValue">
-        <h2>Updating the values</h2>
+        <h3>Updating the values</h3>
     </docs-fragment>
     <p>
         This is similar to changing the value of an entire