Backport PR #4025 on branch 1.12.x (docs(plotting): add inline plot example for highest_expr_genes) (#4035)

Co-authored-by: haoyu-haoyu <85037553+haoyu-haoyu@users.noreply.github.com>

Author: meeseeksmachine

src/scanpy/plotting/_qc.py

@@ -70,6 +70,22 @@ def highest_expr_genes(
     -------
     If `show==False` a :class:`~matplotlib.axes.Axes`.
 
+    Examples
+    --------
+    .. plot::
+        :context: close-figs
+
+        import scanpy as sc
+        adata = sc.datasets.pbmc3k()
+        sc.pl.highest_expr_genes(adata)
+
+    Show only the top 10 genes
+
+    .. plot::
+        :context: close-figs
+
+        sc.pl.highest_expr_genes(adata, n_top=10)
+
     """
     import seaborn as sns  # Slow import, only import if called