Fix indentation in performance analysis notebook

Author: pavelkomarov

examples/4_performance_analysis.ipynb

@@ -81,10 +81,10 @@
    "source": [
     "methods = [(kerneldiff, 'KernelDiff'),\n",
     "\t\t\t(butterdiff, 'ButterDiff'),\n",
-    "\t\t    (finitediff, 'IteratedFD'),\n",
+    "\t\t\t(finitediff, 'IteratedFD'),\n",
     "\t\t\t(polydiff, 'PolyDiff'),\n",
     "\t\t\t(savgoldiff, 'SavGolDiff'),\n",
-    "\t\t    (splinediff, 'SplineDiff'),\n",
+    "\t\t\t(splinediff, 'SplineDiff'),\n",
     "\t\t\t(spectraldiff, 'SpectralDiff'),\n",
     "\t\t\t(rbfdiff, 'RBFDiff'),\n",
     "\t\t\t(tvrdiff, 'TVRDiff'),\n",