Update documentation

* Describe the opening date and balance of the account settings.
* Updated account settings screenshot.

documentation/en/start.html

@@ -81,10 +81,12 @@ <h2>
 
 <p>After an empty ledger is created, you're prompted to set up an account. More accounts are added with the menu item <span class="menu">Account | New…</span>.</p>
 
-<p style="text-align:center"><img src="./images/account_new.png" alt="Creating new accounts" /></p>
+<p style="text-align:center"><img src="./images/account_new.png" alt="Creating a new account" /></p>
 
 <p>First you <span class="menu">Name</span> your new account, here "<i>Bank account</i>".</p>
 
+<p>If you start with an empty account, you can just leave the <span class="menu">Opening date</span> and <span class="menu">Opening balance</span> fields empty. Otherwise you enter a date and amount. If you're starting with a negative balance, toggle the " <span class="button">̶</span> " button.</p>
+
 <p>By default, CapitalBe uses your system settings (configured with Haiku's Locale preferences) for the currency settings and formatting. If you have accounts that differ from that, you can untick the checkbox <span class="menu">Use system currency format</span> to see additional options:</p>
 
 <p>You can choose a currency <span class="menu">Symbol</span>, decide to have it <span class="menu">Appear before amount</span> (otherwise it's shown after), and set the number of <span class="menu">Decimals</span> to use.</p>