doc: comments for codebase and updated documentation

src/features/GetFonts/lib/mapper/mapManagerToParams.ts

@@ -1,6 +1,12 @@
 import type { FontshareParams } from '$entities/Font';
 import type { FilterManager } from '../filterManager/filterManager.svelte';
 
+/**
+ * Maps filter manager to fontshare params.
+ *
+ * @param manager - Filter manager instance.
+ * @returns - Partial fontshare params.
+ */
 export function mapManagerToParams(manager: FilterManager): Partial<FontshareParams> {
     return {
         q: manager.debouncedQueryValue,