Add troubleshooting information

Add mention of SUMMARY_MAX_LENGTH as possible solution for issue with code generation

liquid_tags/Readme.md

@@ -45,6 +45,8 @@ To insert youtube video into a post, enable the
 The width and height are in pixels, and can be optionally specified.  If they
 are not, then the dimensions will be 640 (wide) by 390 (tall).
 
+If you're experiencing issues with code generating (i.e. missing closing tags), add `SUMMARY_MAX_LENGTH = None` to your config.
+
 ## Vimeo Tag
 To insert a Vimeo video into a post, enable the
 ``liquid_tags.vimeo`` plugin, and add to your document:
@@ -54,6 +56,8 @@ To insert a Vimeo video into a post, enable the
 The width and height are in pixels, and can be optionally specified.  If they
 are not, then the dimensions will be 640 (wide) by 390 (tall).
 
+If you're experiencing issues with code generating (i.e. missing closing tags), add `SUMMARY_MAX_LENGTH = None` to your config.
+
 ## Video Tag
 To insert flash/HTML5-friendly video into a post, enable the
 ``liquid_tags.video`` plugin, and add to your document: