[EN-1454] ipf text added

Author: iamishalkin

examples/AllSubscriptionsExample.ipynb

@@ -292,8 +292,14 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Greeks\n",
-    "Details: https://kb.dxfeed.com/display/DS/dxFeed+API+Market+Events#dxFeedAPIMarketEvents-Greeks"
+    "### Option related event types (Greeks, TheoPrice)\n",
+    "Following event types (Greeks, TheoPrice) deal with options. One of the properties of options is expiration, which affects the symbol name in DxFeed symbology. To make this example long-living, we will get a relevant option symbol from the DxFeed IPF service.\n",
+    "\n",
+    "IPF stands for Instrument Profile Format for a normalized view of dxFeed instrument metadata. \n",
+    "You can read more about it at kb.dxfeed.com:\n",
+    "https://kb.dxfeed.com/display/DS/Instrument+Profile+Format+Overview\n",
+    "\n",
+    "https://kb.dxfeed.com/display/DS/How+to+Request+IPF"
    ]
   },
   {
@@ -309,6 +315,14 @@
     "print(option_symbol)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### Greeks\n",
+    "Details: https://kb.dxfeed.com/display/DS/dxFeed+API+Market+Events#dxFeedAPIMarketEvents-Greeks"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,