doc: add note on creating signet

l2l-signet.md

@@ -0,0 +1,69 @@
+Instructions on setting up the signet. This is using Fish shell, but should be
+easy enough to get the gist if using an inferior shell like Bash or Zsh.
+
+1.  Create the appropriate configuration file for our network:
+
+    ```conf
+    signet=1
+
+     # 1 minute block times. Note that /everyone/ who connects to this signet
+     # must have this exact configuration value.
+    signetblocktime=60
+
+    ```
+
+1.  Generate the private key used to sign blocks + corresponding
+    `signetchallenge` value.
+
+    ```fish
+    $ mkdir l2l-signet
+    $ ./build/src/bitcoind -daemon -regtest -datadir=$PWD/l2l-signet
+
+    $ ./build/src/bitcoin-cli -regtest -datadir=$PWD/l2l-signet \
+         createwallet l2l-signet
+
+    $ set signet_challenge (./build/src/bitcoin-cli -regtest -datadir=$PWD/l2l-signet \
+                         getaddressinfo $address | jq -r .scriptPubKey)
+
+    $ echo signetchallenge=$signet_challenge >> l2l-signet/bitcoin.conf
+
+    # Need the wallet descriptors to be able to import the wallet into
+    $ set descriptors (./build/src/bitcoin-cli -regtest -datadir=$PWD/l2l-signet \
+                         listdescriptors true | jq -r .descriptors)
+
+    # We're finished with the regtest wallet!
+    $ ./build/src/bitcoin-cli -regtest -datadir=$PWD/l2l-signet stop
+    ```
+
+1.  Create the signet wallet
+
+    ```fish
+    $ ./build/src/bitcoind -daemon -signet -datadir=$PWD/l2l-signet
+
+    $ ./build/src/bitcoin-cli -signet -datadir=$PWD/l2l-signet \
+         createwallet l2l-signet
+
+    $ ./build/src/bitcoin-cli signet -datadir=$PWD/l2l-signet \
+        importdescriptors "$descriptors"
+
+    ```
+
+1.  Start mining on our network:
+
+    ```fish
+    $ set address (./build/src/bitcoin-cli -signet -datadir=$PWD/l2l-signet getnewaddress)
+
+    $ ./contrib/signet/miner \
+        --cli "bitcoin-cli -signet -datadir=$PWD/l2l-signet" \
+        generate --address $address \
+        --grind-cmd "$PWD/build/src/bitcoin-util grind" \
+        --min-nbits --ongoing --block-interval 60
+    ```
+
+```
+
+```
+
+```
+
+```