Docs: Use something other than the document name to describe a page (#10399)

Our documentation has a history of using a document's name as a way to link to it, such as "See [workers.md]() for details". This makes sense when you're traversing a directory of files, but less sense when the files are abstracted away - as they are on the documentation website.

This PR changes the links to various documentation pages to something that fits better into the surrounding sentence, as you would when making any hyperlink on the web.

docs/systemd-with-workers/README.md

@@ -14,7 +14,7 @@ contains an example configuration for the `federation_reader` worker.
 
 ## Synapse configuration files
 
-See [workers.md](../workers.md) for information on how to set up the
+See [the worker documentation](../workers.md) for information on how to set up the
 configuration files and reverse-proxy correctly.
 Below is a sample `federation_reader` worker configuration file.
 ```yaml