Doc: Add textual descriptions for QtNfc documentation images

Add textual descriptions for annotatedurl.png, annotatedurl2.png,
annotatedurl3.png, and ndefeditor.png in the QtNfc documentation to
ensure QDoc generates alt text.

Pick-to: 6.10 6.9
Fixes: QTBUG-136150
Change-Id: I4ec18fcc7e6a22479173488dd44a00e713a476bd
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

examples/nfc/annotatedurl/doc/src/annotatedurl.qdoc

@@ -14,12 +14,12 @@ Tag. The NDEF message should contain a URI record, an optional \c
 image/* MIME record, and one or more localized Text records.
 
 This is the initial state of the example:
-\image annotatedurl.png
+\image {annotatedurl.png} {Annotated URL NFC main screen}
 
 If a tag is touched, its NDEF content will be shown. Here is the UI
 for a tag that contains a text record and URI record:
 
-\image annotatedurl2.png
+\image {annotatedurl2.png} {Annotated URL NFC tag details}
 
 When the screen is tapped, the URL will be opened in the browser.
 
@@ -61,7 +61,7 @@ is populated as follows:
 
 If the incoming message does not match the filter, an error message is shown:
 
-\image annotatedurl3.png
+\image {annotatedurl3.png} {Annotated URL NFC tag data view}
 
 \note The \l {ndefeditor}{NDEF Editor} example application can be used to create
 the tags with correct or incorrect message structure.

examples/nfc/ndefeditor/doc/src/ndefeditor.qdoc

@@ -19,7 +19,7 @@ NFC tag replaces the manually added records with the NDEF message from the tag.
 If the read operation was cancelled or failed, the NDEF message remains
 unchanged.
 
-\image ndefeditor.png
+\image {ndefeditor.png} {NDEF editor interface}
 
 \sa {Qt NFC}
 */