add a contributing guide

Signed-off-by: strawberry <strawberry@puppygock.gay>

docs/SUMMARY.md

@@ -13,3 +13,4 @@
 - [Appservices](appservices.md)
 - [Development](development.md)
     - [Testing](development/testing.md)
+    - [Contributing](contributing.md)

docs/contributing.md

@@ -0,0 +1 @@
+{{#include ../CONTRIBUTING.md}}

docs/development.md

@@ -1,7 +1,8 @@
 # Development
 
 Information about developing the project. If you are only interested in using
-it, you can safely ignore this section.
+it, you can safely ignore this section. If you plan on contributing, see the
+[contributor's guide](contributing.md).
 
 ## Debugging with `tokio-console`
 

docs/introduction.md

@@ -6,7 +6,7 @@
 
 #### What's different about your fork than upstream Conduit?
 
-See [differences.md](differences.md)
+See the [differences](differences.md) page
 
 #### How can I deploy my own?
 
@@ -14,4 +14,8 @@ See [differences.md](differences.md)
 
 If you want to connect an Appservice to Conduwuit, take a look at the [appservices documentation](appservices.md).
 
+#### How can I contribute?
+
+See the [contributor's guide](contributing.md)
+
 {{#include ../README.md:footer}}