mentions of MIME type guessing in IPFS based plugins' documentation (ref. #62)

plugins/dnslink-ipfs/README.md

@@ -43,3 +43,7 @@ The former can be achieved by running your own IPFS node (using [Kubo](https://g
 The latter could involve using your DNS provider's API to automatically update the relevant `TXT` record, using [DNS Dynamic Update](https://www.rfc-editor.org/rfc/rfc2136) if supported by your DNS provider, or running your own minimal DNS server and delegating `_dnslink` zone to it from your main zone — this is the strategy used for `resilient.is` currently.
 
 One important consideration is the Time-to-live (`TTL`) value on the `_dnslink` `TXT` record: if content updates happen often and need to propagate fast, it needs to be as low as possible, but that will drive more DNS traffic to the nameserver, which might be a consideration. A `TTL` of `900` (15min) is probably a reasonable compromise value to start with.
+
+## Content Type of retrieved content
+
+Content retrieved from IPFS does not have a `Content-Type` header set. To work around this, the plugin takes advantage of the [LibResilient's `guessMimeType()` API](../../docs/ARCHITECTURE.md#mime-type-guessing). Please have a look at that documentation to understand how to use it most effectively.

plugins/gun-ipfs/README.md

@@ -12,3 +12,7 @@ This plugin uses [GunDB](https://gun.eco/) as a source of information on current
 ## Operation
 
 *TBD*
+
+## Content Type of retrieved content
+
+Content retrieved from IPFS does not have a `Content-Type` header set. To work around this, the plugin takes advantage of the [LibResilient's `guessMimeType()` API](../../docs/ARCHITECTURE.md#mime-type-guessing). Please have a look at that documentation to understand how to use it most effectively.

plugins/ipns-ipfs/README.md

@@ -12,3 +12,7 @@ This is a stub of a plugin retrieving content using [IPFS](https://js.ipfs.tech/
 ## Operation
 
 *TBD*
+
+## Content Type of retrieved content
+
+Content retrieved from IPFS does not have a `Content-Type` header set. To work around this, the plugin takes advantage of the [LibResilient's `guessMimeType()` API](../../docs/ARCHITECTURE.md#mime-type-guessing). Please have a look at that documentation to understand how to use it most effectively.