updated intro with description of the newegg 4090 example

README.md

@@ -5,10 +5,57 @@ A change detection server that can notify through various services written in Go
 
 # Intro
 
-GoWatch works through filters, a filter performs certain operations on the input it recieves.  
+GoWatch works through filters, a filter performs operations on the input it recieves.  
 Here is an example of a 'Watch' that calculates the lowest and average price of 4090s on NewEgg and notifies the user if the lowest price changed:  
 ![NewEgg 4090](docs/images/newegg_4090.png)  
 
+Note that everything, including scheduling/storing/notifying, is a `filter`.  
+
+`Schedule` is a [cron](#cron) filter with a '@every 15m' value, so this will run every 15 minutes.  
+
+`NewEgg Fetch` is a [Get URL](#get-url) filter with a 'https://www.newegg.com/p/pl?N=100007709&d=4090&isdeptsrh=1&PageSize=96' value, it's output will be the HTTP response.  
+
+`Select Price` is a [CSS](#css) filter with the value '.item-container .item-action strong[class!="item-buying-choices-price"]' value, it's output will be the html elements containing the prices.  
+An alternative filter type could've been the [XPath](#xpath) filter.
+
+`Sanitize` is a [Replace](#replace) filter, using a regular expression ('[^0-9]') it removes anything that's not a number.  
+
+`Avg` is an [Average](#average) filter, it calculates the average value of its inputs.  
+
+`Min` is a [Minimum](#minimum) filter, it calculates the minimum value of its inputs.  
+
+`Store Avg` and `Store Min` are [Store](#store) filters, they store its input values in the database.  
+
+`Diff` is a [Different Then Last](#different-then-last) filter, only passing on the inputs that are different then the last value stored in the database.  
+
+`Notify` is a [Notify](#notify) filter, if there are any inputs to this filter, it will execute a template and send the result to a user defined 'notifier' (Telegram/Discord/Matrix/etc).
+
+# Filters
+
+## Cron
+
+## Get URL
+
+## CSS
+
+## XPath
+
+## Replace
+
+## Store
+
+## Notify
+
+## Math
+
+### Average
+
+### Minimum
+
+## Condition
+
+### Different Then Last
+
 ## type script compilation
 
 `tsc static/*.ts --lib es2020,dom --watch --downlevelIteration`