docs: added docs to getDefaultProvider; fixes search in Flatworm (#4254).

Author: ricmoo

src.ts/providers/default-provider.ts

@@ -25,6 +25,49 @@ function isWebSocketLike(value: any): value is WebSocketLike {
 
 const Testnets = "goerli kovan sepolia classicKotti optimism-goerli arbitrum-goerli matic-mumbai bnbt".split(" ");
 
+/**
+ *  Returns a default provider for %%network%%.
+ *
+ *  If %%network%% is a [[WebSocketLike]] or string that begins with
+ *  ``"ws:"`` or ``"wss:"``, a [[WebSocketProvider]] is returned backed
+ *  by that WebSocket or URL.
+ *
+ *  If %%network%% is a string that begins with ``"HTTP:"`` or ``"HTTPS:"``,
+ *  a [[JsonRpcProvider]] is returned connected to that URL.
+ *
+ *  Otherwise, a default provider is created backed by well-known public
+ *  Web3 backends (such as [[link-infura]]) using community-provided API
+ *  keys.
+ *
+ *  The %%options%% allows specifying custom API keys per backend (setting
+ *  an API key to ``"-"`` will omit that provider) and ``options.exclusive``
+ *  can be set to either a backend name or and array of backend names, which
+ *  will whitelist **only** those backends.
+ *
+ *  Current backend strings supported are:
+ *  - ``"alchemy"``
+ *  - ``"ankr"``
+ *  - ``"cloudflare"``
+ *  - ``"etherscan"``
+ *  - ``"infura"``
+ *  - ``"publicPolygon"``
+ *  - ``"quicknode"``
+ *
+ *  @example:
+ *    // Connect to a local Geth node
+ *    provider = getDefaultProvider("http://localhost:8545/");
+ *
+ *    // Connect to Ethereum mainnet with any current and future
+ *    // third-party services available
+ *    provider = getDefaultProvider("mainnet");
+ *
+ *    // Connect to Polygoin, but only allow Etherscan and
+ *    // INFURA and use "MY_API_KEY" in calls to Etherscan.
+ *    provider = getDefaultProvider("matic", {
+ *      etherscan: "MY_API_KEY",
+ *      exclusive: [ "etherscan", "infura" ]
+ *    });
+ */
 export function getDefaultProvider(network: string | Networkish | WebSocketLike, options?: any): AbstractProvider {
     if (options == null) { options = { }; }