Update docs with logfile methods

docs/bot-usage.md

@@ -6,9 +6,9 @@ This page explains the different parameters of the bot and how to run it.
 ## Bot commands
 
 ```
-usage: freqtrade [-h] [-v] [--version] [-c PATH] [-d PATH] [-s NAME]
-                 [--strategy-path PATH] [--dynamic-whitelist [INT]]
-                 [--db-url PATH]
+usage: freqtrade [-h] [-v] [--logfile FILE] [--version] [-c PATH] [-d PATH]
+                 [-s NAME] [--strategy-path PATH] [--dynamic-whitelist [INT]]
+                 [--db-url PATH] [--sd-notify]
                  {backtesting,edge,hyperopt} ...
 
 Free, open source crypto trading bot
@@ -22,6 +22,7 @@ positional arguments:
 optional arguments:
   -h, --help            show this help message and exit
   -v, --verbose         Verbose mode (-vv for more, -vvv to get all messages).
+  --logfile FILE        Log to the file specified
   --version             show program's version number and exit
   -c PATH, --config PATH
                         Specify configuration file (default: None). Multiple

docs/configuration.md

@@ -70,6 +70,7 @@ Mandatory Parameters are marked as **Required**.
 | `strategy` | DefaultStrategy | Defines Strategy class to use.
 | `strategy_path` | null | Adds an additional strategy lookup path (must be a folder).
 | `internals.process_throttle_secs` | 5 | **Required.** Set the process throttle. Value in second.
+| `logfile` | | Specify Logfile. Uses a rolling strategy of 10 files, with 1Mb per file.
 | `internals.sd_notify` | false | Enables use of the sd_notify protocol to tell systemd service manager about changes in the bot state and issue keep-alive pings. See [here](installation.md#7-optional-configure-freqtrade-as-a-systemd-service) for more details.
 
 ### Parameters in the strategy