docs: mention max-filesize options also apply to MQTT transfers

Also make it clearer that the caveat 'if the file size is unknown it
the option will have no effect' may apply to protocols other than FTP
and HTTP.

Reported-by: Josh Soref

Fixes https://github.com/curl/curl/issues/7453

docs/cmdline-opts/max-filesize.d

@@ -12,6 +12,6 @@ A size modifier may be used. For example, Appending 'k' or 'K' will count the
 number as kilobytes, 'm' or 'M' makes it megabytes, while 'g' or 'G' makes it
 gigabytes. Examples: 200K, 3m and 1G. (Added in 7.58.0)
 
-**NOTE**: The file size is not always known prior to download, and for such
-files this option has no effect even if the file transfer ends up being larger
-than this given limit. This concerns both FTP and HTTP transfers.
+**NOTE**: For protocols where the size is not known in advance (including FTP
+and HTTP) this option has no effect even if the file transfer ends up being
+larger than the given limit.

docs/libcurl/opts/CURLOPT_MAXFILESIZE.3

@@ -33,15 +33,15 @@ Pass a long as parameter. This allows you to specify the maximum \fIsize\fP
 this value, the transfer will not start and \fICURLE_FILESIZE_EXCEEDED\fP will
 be returned.
 
-The file size is not always known prior to download, and for such files this
-option has no effect even if the file transfer ends up being larger than this
-given limit. This concerns both FTP and HTTP transfers.
+For protocols where the size is not known in advance (including FTP and HTTP)
+this option has no effect even if the file transfer ends up being larger than
+the given limit.
 
 If you want a limit above 2GB, use \fICURLOPT_MAXFILESIZE_LARGE(3)\fP.
 .SH DEFAULT
 None
 .SH PROTOCOLS
-FTP and HTTP
+FTP, HTTP and MQTT
 .SH EXAMPLE
 .nf
 CURL *curl = curl_easy_init();

docs/libcurl/opts/CURLOPT_MAXFILESIZE_LARGE.3

@@ -35,13 +35,13 @@ Pass a curl_off_t as parameter. This allows you to specify the maximum
 larger than this value, the transfer will not start and
 \fICURLE_FILESIZE_EXCEEDED\fP will be returned.
 
-The file size is not always known prior to download, and for such files this
-option has no effect even if the file transfer ends up being larger than this
-given limit. This concerns both FTP and HTTP transfers.
+For protocols where the size is not known in advance (including FTP and HTTP)
+this option has no effect even if the file transfer ends up being larger than
+the given limit.
 .SH DEFAULT
 None
 .SH PROTOCOLS
-FTP and HTTP
+FTP, HTTP and MQTT
 .SH EXAMPLE
 .nf
 CURL *curl = curl_easy_init();