Update docs re: bot_loop_start in backtest

docs/bot-basics.md

@@ -57,10 +57,10 @@ This loop will be repeated again and again until the bot is stopped.
 
 * Load historic data for configured pairlist.
 * Calls `bot_start()` once.
-* Calls `bot_loop_start()` once.
 * Calculate indicators (calls `populate_indicators()` once per pair).
 * Calculate entry / exit signals (calls `populate_entry_trend()` and `populate_exit_trend()` once per pair).
 * Loops per candle simulating entry and exit points.
+  * Calls `bot_loop_start()` strategy callback.
   * Check for Order timeouts, either via the `unfilledtimeout` configuration, or via `check_entry_timeout()` / `check_exit_timeout()` strategy callbacks.
   * Calls `adjust_entry_price()` strategy callback for open entry orders.
   * Check for trade entry signals (`enter_long` / `enter_short` columns).

docs/strategy-callbacks.md

@@ -51,7 +51,8 @@ During hyperopt, this runs only once at startup.
 
 ## Bot loop start
 
-A simple callback which is called once at the start of every bot throttling iteration (roughly every 5 seconds, unless configured differently).
+A simple callback which is called once at the start of every bot throttling iteration in dry/live mode (roughly every 5
+seconds, unless configured differently) or once per candle in backtest/hyperopt mode.
 This can be used to perform calculations which are pair independent (apply to all pairs), loading of external data, etc.
 
 ``` python