customer_gates.ipynb - minor content cleanup (quantumlib#5215)

cc @tanujkhattar

Author: verult

docs/custom_gates.ipynb

@@ -485,9 +485,9 @@
    },
    "source": [
     "As mentioned, methods such as `_unitary_` which we have seen are known as \"magic\n",
-    "methods.\" Much of cirq relies on \"magic methods\", which are methods prefixed with one or\n",
-    "two underscores and used by cirq's protocols or built-in python methods.\n",
-    "For instance,  python translates `cirq.Z**0.25` into\n",
+    "methods.\" Much of Cirq relies on \"magic methods\", which are methods prefixed with one or\n",
+    "two underscores and used by Cirq's protocols or built-in Python methods.\n",
+    "For instance,  Python translates `cirq.Z**0.25` into\n",
     "`cirq.Z.__pow__(0.25)`.  Other uses are specific to cirq and are found in the\n",
     "protocols subdirectory.  They are defined below.\n",
     "\n",
@@ -502,11 +502,11 @@
     "id": "d05fa2e8d1ab"
    },
    "source": [
-    "### Standard python magic methods\n",
+    "### Standard Python magic methods\n",
     "\n",
-    "There are many standard magic methods in python.  Here are a few of the most\n",
-    "important ones used in cirq:\n",
-    "  * `__str__` for user-friendly string output and  `__repr__` is the python-friendly string output, meaning that `eval(repr(y))==y` should always be true.\n",
+    "There are many standard magic methods in Python.  Here are a few of the most\n",
+    "important ones used in Cirq:\n",
+    "  * `__str__` for user-friendly string output and  `__repr__` is the Python-friendly string output, meaning that `eval(repr(y))==y` should always be true.\n",
     "  * `__eq__` and `__hash__` which define whether objects are equal or not.  You\n",
     "  can also use `cirq.value.value_equality` for objects that have a small list\n",
     "  of sub-values that can be compared for equality.\n",
@@ -552,7 +552,7 @@
     "These gates can be understood by the simulator, optimizers, and other code.\n",
     "3. All that matters is functional equivalence.\n",
     "Don't worry about staying within or reaching a particular gate set; it's too hard to predict what the caller will want. Gate-set-aware decomposition is useful, but *this is not the protocol that does that*.\n",
-    "Gate-set-aware decomposition may be added in the future, but doesn't exist within Cirq at the moment.\n",
+    "Instead, use features available in the [transformer API](transform.ipynb#compiling_to_nisq_targets_cirqcompilationtargetgateset).\n",
     "\n",
     "For example, `cirq.CCZ` decomposes into a series of `cirq.CNOT` and `cirq.T` operations.\n",
     "This allows code that doesn't understand three-qubit operation to work with `cirq.CCZ`; by decomposing it into operations they do understand.\n",