update README

Fixes #4

README.md

@@ -13,17 +13,30 @@ Unofficial APIs for Investing.com website.
 ### getHistoricalData
 Not all parameters are mandatory.
 
-- **input** String: input string, provide a valid investing.com pairId. (Required)
-- **resolution** String: resolution of the response.
-  - Valid values: 
-    - `5` (5 minutes)
-    - `60` (1 hour)
-    - `300` (5 hours)
-    - `D` (1 day, **Default**)
-    - `W` (week)
-    - `M` (month)
-- **from** Date: a Date object to indicate the start of the period (Required)
-- **to** Date: a Date object to indicate the end of the period (Required)
+#### Input params
+- **params** Object (required)
+  - **input** String: input string, provide a valid investing.com pairId. (Required)
+  - **resolution** String: resolution of the response.
+    - Valid values: 
+      - `5` (5 minutes)
+      - `60` (1 hour)
+      - `300` (5 hours)
+      - `D` (1 day, **Default**)
+      - `W` (week)
+      - `M` (month)
+  - **from** Date: a Date object to indicate the start of the period (Required)
+  - **to** Date: a Date object to indicate the end of the period (Required)
+
+#### Output
+```js
+{
+  date: number;        // Timestamp of the data point
+  price_open: number;  // Opening price
+  price_high: number;  // Highest price during the period
+  price_low: number;   // Lowest price during the period
+  price_close: number; // Closing price
+}[]
+```
 
 #### Example
 ```js
@@ -68,14 +81,14 @@ Response
 
 ### searchQuotes
 
-Input params:
+#### Input params
 - **search** String (required)
 - **options** Object (optional)
   - **filters** Object (optional)
     - **type** String (optional)
     - **exchange** Array of Strings (optional)
 
-Output:
+#### Output
 ```js
 { 
   pairId:      number;