Fix error in docs (#925)

The function is called `clearCacheById()`
https://github.com/jaredwray/cacheable/blob/8ea2b079cdec11c6f068fb8a116e8561f42fa1c5/packages/flat-cache/src/index.ts#L462

packages/flat-cache/README.md

@@ -107,7 +107,7 @@ In version 6 we attempted to keep as much as the functionality as possible which
 
 - `create(options?: FlatCacheOptions)` - Creates a new cache and will load the data from disk if it exists
 - `createFromFile(filePath, options?: FlatCacheOptions)` - Creates a new cache from a file
-- `clearByCacheId(cacheId: string, cacheDir?: string)` - Clears the cache by the cacheId
+- `clearCacheById(cacheId: string, cacheDir?: string)` - Clears the cache by the cacheId
 - `clearAll(cacheDirectory?: string)` - Clears all the caches