Improve FTS docs (#140)

Add an important note and clean up other docs.

Author: stephencelis

Sources/StructuredQueriesCore/SQLite/FTS5.swift

@@ -2,7 +2,9 @@ import IssueReporting
 
 /// A virtual table using the FTS5 extension.
 ///
-/// Apply this protocol to a `@Table` declaration to introduce FTS5 helpers.
+/// Apply this protocol to a `@Table` declaration to introduce [FTS5] helpers.
+///
+/// [FTS5]: https://www.sqlite.org/fts5.html
 public protocol FTS5: Table {}
 
 extension TableDefinition where QueryValue: FTS5 {
@@ -13,6 +15,16 @@ extension TableDefinition where QueryValue: FTS5 {
   /// // SELECT … FROM "reminderTexts" WHERE ("reminderTexts" MATCH 'get')
   /// ```
   ///
+  /// > Important: Avoid passing a string entered by the user directly to this operator. FTS5
+  /// > queries have a distinct [syntax] that can specify particular columns and refine a search in
+  /// > various ways. If FTS5 is given a query with invalid syntax, it can even throw SQL errors at
+  /// > runtime.
+  /// >
+  /// > Instead, consider transforming the user's input into a query by quoting, prefixing, and/or
+  /// > combining inputs from your UI into a valid query before handing it off to SQLite.
+  ///
+  /// [syntax]: https://www.sqlite.org/fts5.html#full_text_query_syntax
+  ///
   /// - Parameter pattern: A string expression describing the `MATCH` pattern.
   /// - Returns: A predicate expression.
   public func match(_ pattern: some StringProtocol) -> some QueryExpression<Bool> {
@@ -60,7 +72,7 @@ extension TableColumnExpression where Root: FTS5 {
   ///
   /// ```swift
   /// ReminderText.where { $0.title.match("get") }
-  /// // SELECT … FROM "reminderTexts" WHERE ("reminderTexts"."title" MATCH 'get')
+  /// // SELECT … FROM "reminderTexts" WHERE ("reminderTexts" MATCH 'title:\"get\"')
   /// ```
   ///
   /// - Parameter pattern: A string expression describing the `MATCH` pattern.