Add deep nesting clarification to docs generator

doc/mavlink_gitbook.py

@@ -40,11 +40,11 @@
 index_text+='\n\nMAVLink messages are defined in XML files in the [mavlink/message definitions](https://github.com/mavlink/mavlink/blob/master/message_definitions/) folder. The messages that are common to all systems are defined in [common.xml](https://github.com/mavlink/mavlink/blob/master/message_definitions/v1.0/common.xml) (only messages contained in this file are considered standard messages).'
 index_text+='\n\nThe common messages are provided as human-readable tables in: [Common](../messages/common.md).'
 index_text+='\n\n## Vendor Specific Extensions (Dialects) {#dialects}'
-index_text+='\n\nMAVLink protocol-specific and vendor-specific messages (dialects) are stored in separate XML files. These often extend (include) the [common](../messages/common.md) messages.'
-index_text+='\n\n> **Note** Vendor forks of MAVLink may contain messages that are not yet merged, and hence will not appear in this documentation.'
+index_text+='\n\nMAVLink protocol-specific and vendor-specific messages (dialects) are stored in separate XML files. These often include the [common](../messages/common.md) message definition, extending it with needed vendor or protocol specific messages.'
+index_text+='\n\n> **Note** While a dialect can include any other message definition, care should be taken when including a definition file that includes another file (only a single level of nesting is tested).'
+index_text+='\n\n<span></span>\n> **Note** Vendor forks of MAVLink may contain messages that are not yet merged, and hence will not appear in this documentation.'
 index_text+='\n\nThe human-readable forms of the vendor XML files are linked below:'
 
-
 #Fix up the BeautifulSoup output so to fix build-link errors in the generated gitbook.
 ## BS puts each tag/content in its own line. Gitbook generates anchors using the spaces/newlines. 
 ## This puts displayed text content immediately within tags so that anchors/links generate properly