Clarify documentation wrt setting values

[svillar]

The current documentation is a bit confusing with regard to how to set operation modes. I have doubts with some topics

1. in the Read values section we have /heat/operation/set
   That looks like a topic to set a value instead of a topic to read a value from. Actually after subscribing to that topic I get nothing (contrary to subscribing to /heat/operation where I do get values). So what is it used for?
2. in the Change values section, there is no payload specification for any topic except /water/temp/set. I've verified that an empty payload does indeed change the values. Perhaps that should be added in the documentation.
3. Related to the previous comment, what about having just /heat/operation to read values and /heat/operation/set to set values (the payload would the 0/1 to disable/enable, or whatever other pair like off/on...)
4. Last but not least, what does imply setting an operating mode on? For example for water, if I set /water/operation/on does it simply enable the hot water system (which will eventually kick in when needed), or does it actually start to warm the water?

[ronhks]

Actually I have a huge load, i will answer later (approx end of August/September).