proposal docs for podcast:chat tag

proposal-docs/chat/chatprotocols.txt

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+irc
+xmpp
+nostr
+matrix

proposal-docs/chat/social.md

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+# The "podcast:chat" Specification
+
+<small>Version 1.0 by Dave Jones - 2022.04.10</small>
+
+<br>
+
+## Purpose
+The `<podcast:chat>` tag allows a podcaster to attach information to either the `channel` or an `item` about where the
+"official" chat for either the podcast or a specific episode is to be found.  Just like `<podcast:socialInteract>`
+functions for social media, the `chat` tag will function for ephemeral chat.  There are many protocols in use across
+the internet for chat based communication.  This tag is meant to be flexible enough to adapt to whichever protocol the
+podcaster wants to use.
+
+This tag can exist at the `channel` or `item` level.  It's presence at a particular level governs how it should be
+treated.  If found at the `item` level, this should be treated as the information for that specific episode,
+overriding what is at the `channel` level.  If this tag is found at the `channel` level, it would be considered the
+chat for the entire podcast and is recommended to be an "always on" chat room experience.
+
+If a podcast has an "always on" style chat service it is recommended to link that at the `channel` level and do not
+use the `<podcast:chat>` tag at the `item` level.
+
+## Chat Element
+`<podcast:chat>`<br><br>
+
+### Parent
+&nbsp; `<item>` or `<channel>`
+
+### Count
+&nbsp; Single
+
+### Attributes
+- **server** (required) The fqdn of a chat server that serves as the "bootstrap" server to connect to.
+- **protocol** (required) The [protocol](/chatprotocols.txt) in use on the server.
+- **accountId** (recommended) The account id of the podcaster on the server or platform being connected to.
+- **space** (optional) Some chat systems have a notion of a chat "space" or "room" or "topic". This attribute will serve
+  that purpose.
+
+
+Example (IRC):
+```xml
+<podcast:chat 
+    server="irc.zeronode.net" 
+    protocol="irc" 
+    accountId="@jsmith" 
+    space="#myawesomepodcast" 
+/>
+```
+
+Example (XMPP):
+```xml
+<podcast:chat 
+    server="jabber.example.com"
+    protocol="xmpp"
+    accountId="jsmith@jabber.example.org" 
+    space="myawesomepodcast@jabber.example.org" 
+/>
+```
+
+Example (Nostr):
+```xml
+<podcast:chat 
+    server="relay.example.com" 
+    protocol="nostr" 
+    accountId="npub1pvdw7mm7k20t9dn9gful8n5xua5yv8rmgd9wul88qq5dxj80lpxqd39r3u"
+    space="#myawesomepodcast_episode129" 
+/>
+```
+
+Discussions:
+- https://github.com/Podcastindex-org/podcast-namespace/discussions/502