Added linking between QDN websites / apps.

The simplest way to link to another QDN website is to include a link with the format:
<a href="qortal://WEBSITE/QortalDemo">link text</a>

This can be expanded to link to a specific path, e.g:
<a href="qortal://WEBSITE/QortalDemo/minting-leveling/index.html">link text</a>

Or it can be initiated programatically, via qortalRequest():

let res = await qortalRequest({
    action: "LINK_TO_QDN_RESOURCE",
    service: "WEBSITE",
    name: "QortalDemo",
    path: "/minting-leveling/index.html" // Optional
});

Note that qortal:// links don't yet support identifiers, so the above format is not confirmed.

Q-Apps.md

@@ -77,6 +77,7 @@ Here is a list of currently supported actions:
 - FETCH_BLOCK_RANGE
 - SEARCH_TRANSACTIONS
 - GET_PRICE
+- LINK_TO_QDN_RESOURCE
 
 More functionality will be added in the future.
 
@@ -403,6 +404,27 @@ let res = await qortalRequest({
 });
 ```
 
+### Link/redirect to another QDN website
+Note: an alternate method is to include `<a href="qortal://WEBSITE/QortalDemo">link text</a>` within your HTML code.
+```
+let res = await qortalRequest({
+    action: "LINK_TO_QDN_RESOURCE",
+    service: "WEBSITE",
+    name: "QortalDemo",
+});
+```
+
+### Link/redirect to a specific path of another QDN website
+Note: an alternate method is to include `<a href="qortal://WEBSITE/QortalDemo/minting-leveling/index.html">link text</a>` within your HTML code.
+```
+let res = await qortalRequest({
+    action: "LINK_TO_QDN_RESOURCE",
+    service: "WEBSITE",
+    name: "QortalDemo",
+    path: "/minting-leveling/index.html"
+});
+```
+
 
 ## Sample App