doc: minor improvements to xmldocs and readme

Chickensoft.Log/src/FileWriter.cs

@@ -19,7 +19,8 @@ public sealed class FileWriter : ILogWriter {
   private static string _defaultFileName = "output.log";
   /// <summary>
   /// The default file name that will be used when creating a
-  /// <see cref="FileWriter"/> if no filename is specified.
+  /// <see cref="FileWriter"/> if no filename is specified. Defaults to
+  /// "output.log".
   /// </summary>
   /// <remarks>
   /// This default may be changed. If it is changed after a default
@@ -89,7 +90,7 @@ public static FileWriter Instance() {
   private readonly object _writingLock = new();
 
   /// <summary>
-  /// The path of the filename this Writer is writing to.
+  /// The path of the file this Writer is writing to.
   /// </summary>
   public string FileName { get; }
 

README.md

@@ -90,12 +90,13 @@ public class MyClass
 > may not. For instance, the `TraceWriter` has separate channels for regular log
 > messages, warnings, and errors. The `FileWriter` has only one channel, the
 > file it's writing to. Warnings and errors can still be distinguished by the
-> label the formatter gives them.
+> label the formatter gives them, even if directed to the same channel as regular
+> log messages.
 
 ### Formatting
 
 Optionally, when constructing a log, you can provide an `ILogFormatter` that the
-log will use to format each log message. (The formatted message should include
+log will use to format each message. (The formatted message should include
 the log's name, the level of the message, and the message itself.)
 
 ```csharp