docs: answering questions: explorer & api client

src/pages/stacks-blockchain/managing-accounts.md

@@ -36,6 +36,8 @@ First install the stacks transactions library and an API client for the [Stacks
 npm install --save @blockstack/stacks-transactions@0.6.0 @stacks/blockchain-api-client
 ```
 
+-> The API client is generated from the [OpenAPI specification](https://github.com/blockstack/stacks-blockchain-api/blob/master/docs/openapi.yaml) ([openapi-generator](https://github.com/OpenAPITools/openapi-generator)). Many other languages and frameworks are be supported by the generator.
+
 ## Step 2: Generating an account
 
 To get started, let's generate a new, random Stacks 2.0 private key:

src/pages/stacks-blockchain/overview.md

@@ -20,6 +20,8 @@ replica as all other peers.
 _Non-enumerable_ means that the set of peers that are producing the blocks don’t know about one another — they don’t know
 their identities, or even how many exist and are online. They are indistinguishable.
 
+-> The Stacks 2.0 blockchain is open-source and available on GitHub: [blockstack/stacks-blockstack](https://github.com/blockstack/stacks-blockchain).
+
 ## Status
 
 The Stacks 2.0 blockchain is in active development. While the final release ("mainnet") is in the works, you can already get familiar with Stacks 2.0 capabilities on the "testnet".
@@ -29,6 +31,12 @@ For more information on the testnet, have a look at this page:
 [@page-reference | inline]
 | /stacks-blockchain/testnet
 
+## Explorer
+
+You can view accounts, blocks, transactions, and smart contracts broadcasted to the Stacks 2.0 blockchain using the [**Stacks 2.0 Explorer**](https://testnet-explorer.blockstack.org/).
+
+-> The Explorer consumes the [Stacks 2.0 Blockchain API](https://blockstack.github.io/stacks-blockchain-api/). You can use this public API for programatic access to the blockchain.
+
 ## Tutorials
 
 [@page-reference | grid-small]

src/pages/stacks-blockchain/sending-tokens.md

@@ -39,6 +39,8 @@ First install the stacks transactions library, a JavaScript [BigNum](https://en.
 npm install --save @blockstack/stacks-transactions@0.6.0 bn.js @stacks/blockchain-api-client
 ```
 
+-> The API client is generated from the [OpenAPI specification](https://github.com/blockstack/stacks-blockchain-api/blob/master/docs/openapi.yaml) ([openapi-generator](https://github.com/OpenAPITools/openapi-generator)). Many other languages and frameworks are be supported by the generator.
+
 ## Step 2: Specifying a sender
 
 In order to build and sign transactions, you will need a Stacks privat key. You can easily generate a new, random Stacks 2.0 sender key (see ["Generating an account" from the previous tutorial](http://localhost:3000/stacks-blockchain/managing-accounts#step-2-generating-an-account)).