docs: --datadir documentation

docs/backtesting.md

@@ -46,6 +46,11 @@ python3 ./freqtrade/main.py backtesting --realistic-simulation --refresh-pairs-c
 python3 ./freqtrade/main.py backtesting --realistic-simulation --live
 ```
 
+**Using a different on-disk ticker-data source**
+```bash
+python3 ./freqtrade/main.py backtesting --datadir freqtrade/tests/testdata-20180101
+```
+
 For help about backtesting usage, please refer to 
 [Backtesting commands](#backtesting-commands).
 

docs/bot-usage.md

@@ -26,6 +26,9 @@ optional arguments:
                         specify configuration file (default: config.json)
   -v, --verbose         be verbose
   --version             show program's version number and exit
+  -dd PATH, --datadir PATH
+                        Path is from where backtesting and hyperopt will load the
+                        ticker data files (default freqdata/tests/testdata).
   --dynamic-whitelist [INT]
                         dynamically generate and update whitelist based on 24h
                         BaseVolume (Default 20 currencies)

docs/hyperopt.md

@@ -163,6 +163,11 @@ We strongly recommend to use `screen` to prevent any connection loss.
 python3 ./freqtrade/main.py -c config.json hyperopt
 ```
 
+### Execute hyperopt with different ticker-data source
+If you would like to learn parameters using an alternate ticke-data that
+you have on-disk, use the --datadir PATH option. Default hyperopt will
+use data from directory freqtrade/tests/testdata.
+
 ### Hyperopt with MongoDB
 Hyperopt with MongoDB, is like Hyperopt under steroids. As you saw by
 executing the previous command is the execution takes a long time.