PyDoc: Set max width to 1000px

While not full width this gives a nice trade off between improved screen 
use space and readibility.
The old value was 80 so this gives 25% more screen space.

See T73223

doc/python_api/static/css/theme_overrides.css

@@ -9,3 +9,7 @@
 /* Hide home icon in search area */
 .wy-side-nav-search > a:hover {background: none; opacity: 0.9}
 .wy-side-nav-search > a.icon::before {content: none}
+
+.wy-nav-content {
+    max-width: 1000px !important;
+}