Document use of http-path in multiaddr (#119)

Author: gammazero

README.md

@@ -62,6 +62,7 @@ ipni ads get --ai=/ip4/76.219.232.45/tcp/24001/p2p/12D3KooWPNbkEgjdBNeaCGpsgCrPR
 ```sh
 cat ad-cids-list.txt | ipni add get /dns4/ads.example.com/tcp/24001/p2p/<publisher-p2p-id>
 ```
+
 ### `ads list`
 - List the 10 most recent advertisements from a provider:
 ```sh
@@ -81,6 +82,8 @@ ipni ads dist --ai=/ip4/76.219.232.45/tcp/24001/p2p/12D3KooWPNbkEgjdBNeaCGpsgCrP
     --end=baguqeerage4rh6yqy4u37x7i337q57wrwfls5ihiei6l72rr6ezrw5vcucea
 ```
 
+**Note* To include an HTTP path prefix in the `addr-info` flag of the `ads` command, include the `http-path` component in the multiaddr. For example, `--ai /dns/pool.example.com/https/http-path/eu%2Fprovider1/p2p/12D3KooWPMGfQs5CaJKG4yCxVWizWBRtB85gEUwiX2ekStvYvqgp` fetches ads from `https://pool.example.com/eu/provider1/ipni/v1/ad/head`. Any "/" within the http-path must be escaped.
+
 ### `find`
 - Ask cid.contact where to find CID `bafybeigvgzoolc3drupxhlevdp2ugqcrbcsqfmcek2zxiw5wctk3xjpjwy`:
 ```sh

pkg/ads/flags.go

@@ -8,9 +8,10 @@ import (
 
 var addrInfoFlag = &cli.StringFlag{
 	Name: "addr-info",
-	Usage: "Publisher's address info in form of libp2p multiaddr info.\n" +
-		"Example ipnisync: /ip4/1.2.3.4/tcp/1234/p2p/12D3KooWE8yt84RVwW3sFcd6WMjbUdWrZer2YtT4dmtj3dHdahSZ\n" +
-		"Example HTTP:     /ip4/1.2.3.4/tcp/1234/http/p2p/12D3KooWE8yt84RVwW3sFcd6WMjbUdWrZer2YtT4dmtj3dHdahSZ",
+	Usage: "Publisher's address info in form of libp2p multiaddr info. Examples:\n" +
+		"ipnisync:  /ip4/1.2.3.4/tcp/1234/p2p/12D3KooWE8yt84RVwW3sFcd6WMjbUdWrZer2YtT4dmtj3dHdahSZ\n" +
+		"HTTP:      /ip4/1.2.3.4/tcp/1234/http/p2p/12D3KooWE8yt84RVwW3sFcd6WMjbUdWrZer2YtT4dmtj3dHdahSZ\n" +
+		"HTTP path: /ip4/1.2.3.4/tcp/1234/http/http-path/myprovidrs%2Fprov1/p2p/12D3KooWE8yt84RVwW3sFcd6WMjbUdWrZer2YtT4dmtj3dHdahSZ",
 	Aliases:  []string{"ai"},
 	Required: true,
 }