Removed unused extensions.

Author: electricessence

Source/Extensions.StringSegment.cs

@@ -46,16 +46,6 @@ public static StringSegment AsSegment(this string buffer, int offset, int length
 	public static StringSegmentEnumerable AsEnumerable(this StringSegment segment)
 		=> new(segment);
 
-	/// <summary>
-	/// Creates a <see cref="CharacterSequence"/> from the provided <paramref name="sequence"/>.
-	/// </summary>
-	public static CharacterSequence AsCharacterSequence(this IReadOnlyCollection<char> sequence)
-		=> sequence is null ? CharacterSequence.Empty : CharacterSequence.Create(()=>sequence.Count, sequence!);
-
-	/// <inheritdoc cref="AsCharacterSequence(IReadOnlyCollection{char})" />
-	public static CharacterSequence AsCharacterSequence(this ICollection<char> sequence)
-		=> CharacterSequence.Create(sequence?.Count ?? 0, sequence!);
-
 	/// <summary>
 	/// Finds the first instance of a string and returns a StringSegment for subsequent use.
 	/// </summary>

Source/StringBuilderHelper.cs

@@ -149,7 +149,7 @@ public static implicit operator StringBuilderHelper(StringBuilder value)
         => value is null ? new() : new(new StringBuilder(value.Length).Append(value));
 
     /// <summary>
-    /// Converts the <see cref="StringConcat"/> instance to a string.
+    /// Converts the <see cref="StringBuilderHelper"/> instance to a string.
     /// </summary>
 #if NETSTANDARD2_0
 #else