New Rule

1 
<rule id="ID" name="Commonly Confused Words">    
 <pattern>
  <token>Its</token>
 </pattern>
 <message><suggestion>Check the meaning of this word to be sure you are using the word correctly. Words that sound alike are often confused with one another.</suggestion></message>
 <url>http://i.imgur.com/rwi0HDh.png</url>
  <example type='incorrect'><marker>Its</marker> really hard sometimes.</example>
 <example type='correct'>It's really hard sometimes.</example>
</rule>

(Note: I don’t know it this is 100% fine. There must be a mistake on it.)

2

Thanks for your rule suggestion. We already have rules for “it’s vs. its”, you can find them here:
http://community.languagetool.org/rule/list?offset=0&max=10&lang=en&filter=its&categoryFilter=&_action_list=Filter

If you can come up with rules that refine our existing rules, that would be great. Your rule would give a message about every occurrence of “Its”, which will cause several false alarms and we’re trying to avoid those.

3 
<rule id="ID" name="Comprised of">    
 <pattern>
  <token>comprised</token>
  <token>of</token>
 </pattern>
 <message>Instead use <suggestion>composed of</suggestion> or <suggestion>consists of</suggestion> as appropriate.</message>
 <url>http://www.mirror.co.uk/news/technology-science/technology/man-makes-47000-wikipedia-edits-5106883</url>
 <example correction=''>The house is <marker>comprised of</marker> three bedrooms and a bathroom.</example>
 <example>The house is  composed of three bedrooms and a bathroom.</example>
</rule>