docs(text): add module doc (#4812)

text/mod.ts

@@ -1,6 +1,31 @@
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
 // This module is browser compatible.
 
+/**
+ * @module
+ * Utility functions for working with text.
+ *
+ * There are various functions for manipulating text, such as `toCamelCase`:
+ *
+ * ```ts
+ * import { toCamelCase } from "@std/text/case";
+ *
+ * console.log(toCamelCase("snake_case")); // "snakeCase"
+ * ```
+ *
+ * Or for comparing strings:
+ *
+ * ```ts
+ * import { compareSimilarity } from "@std/text/compare-similarity";
+ * const words = ["hi", "hello", "help"];
+ *
+ * // words most-similar to "hep" will be at the front
+ * words.sort(compareSimilarity("hep"));
+ * ```
+ *
+ * This module is browser compatible.
+ */
+
 export * from "./levenshtein_distance.ts";
 export * from "./closest_string.ts";
 export * from "./compare_similarity.ts";