Temporarily change README to use relative URL…

for screenshot `src`.

This should help someone verify pulsar-edit/pulsar#1375.

Author: savetheclocktower

README.md

@@ -2,9 +2,7 @@
 
 Contextual hints for Pulsar.
 
-<p>
-  <img width="520" alt="pulsar-hover screenshot" src="https://raw.githubusercontent.com/savetheclocktower/pulsar-hover/main/docs/screenshot.png" />
-</p>
+![pulsar-hover screenshot](./docs/screenshot.png)
 
 Designed as a replacement for both `atom-ide-datatip` and `atom-ide-signature-help`.