Move data from Raspberry pi to a synology diskstation to present in a webpage
I'm not experiment on this topic but what I would do is setup a database in between (on the Synology rather than on the Raspberry Pi). Let's call your Synology server, and Raspberry Pi a sensor client.
I would host a database on the server, and push the from the sensor client. The data would be pushed either using an API through webservices or a more low level if you need it faster (some code needed on server side for this) or, since the client computer is under your control, it could directly push in the database.
Your concrete choice between database, webservice or other API depends on:

How much data have to be pushed?
How fast data have to pushed?
How much do you trust your network?
How much do you trust your sensor client?

I've never used it but I suggest you use SQLAlchemy for connecting to the database (from both side). 
If in some use case the remote server can be down, the sensor client would store sensor data in some local file and push them when the server come back online.
I'm looking for ideas, on how to display sensor data in a webpage, hosted by a Synology Diskstation, where the data comes from sensors connected to a Raspberry pi. This is going to be implemented in Python.
I have put together the sensors, and have these connected to the Raspberry. I have also the Python code, so I can read the sensors.  I have a webpage up and running on the Diskstation using Python. But how do I get the data from the  rasp to the Diskstation. The reading is just done, when the webpage is displayed.
Guess some kind of WebServices on the Rasp ? I have looked at Pyro4, but doesn't look like it can be installed at the Diskstation. And I would prefer not to install a whole WebServer Framework on the rasp.
Do you have a suggestion ?