Add help page for the SQL console.

src/main/java/com/andrewlalis/perfin/PerfinApp.java

@@ -107,6 +107,7 @@ public class PerfinApp extends Application {
             helpRouter.map("adding-a-transaction", PerfinApp.class.getResource("/help-pages/adding-a-transaction.fxml"));
             helpRouter.map("profiles", PerfinApp.class.getResource("/help-pages/profiles.fxml"));
             helpRouter.map("about", PerfinApp.class.getResource("/help-pages/about.fxml"));
+            helpRouter.map("sql-console", PerfinApp.class.getResource("/help-pages/sql-console.fxml"));
         });
     }
 

src/main/resources/help-pages/home.fxml

@@ -33,5 +33,7 @@
         [Adding a Transaction](help:adding-a-transaction)
         --
         [Profiles](help:profiles)
+        --
+        [SQL Console](help:sql-console)
     </StyledText>
 </VBox>

src/main/resources/help-pages/sql-console.fxml

@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import com.andrewlalis.perfin.view.component.StyledText?>
+<?import javafx.scene.layout.VBox?>
+<VBox xmlns="http://javafx.com/javafx"
+      xmlns:fx="http://javafx.com/fxml"
+>
+    <StyledText>
+        ## SQL Console ##
+        * This feature is for advanced users with experience in relational
+        databases. *
+        --
+        The SQL console is a page where you can write and execute custom SQL
+        queries on the underlying database that your Perfin profile is using.
+        --
+        Unless otherwise noted, Perfin uses the [H2 Database](https://www.h2database.com/html/main.html),
+        but for most common purposes, the SQL query syntax is identical to other
+        common dialects.
+        --
+        Simply write your queries in the upper text area, press **Execute**, and
+        view the results in the output area below. When running multiple queries,
+        be sure to end each with a semicolon (`;`). Results are shown as comma
+        separated columns of text, starting with an initial row for the column
+        names.
+
+        # Comments #
+        Prepend your query with `#` or `//` to exclude it from execution. Each
+        comment character disables all query syntax up until the next semicolon,
+        (`;`).
+    </StyledText>
+</VBox>