Remove initial included license and add CC-BY 4.0

Relequestual · Relequestual · commit 91d513397b1a · 2023-08-03T10:42:53.000+01:00
Initial license was from the Webhint.io governance document, but governance aspects have since been moved to another document, leaving us free to choose the license for the charter.
diff --git a/CHARTER.md b/CHARTER.md
@@ -105,4 +105,4 @@ TSC: The JSON Schema Technical Steering Committee, delegated technical leadershi
 
 ---
 
-This work is licensed under a [Creative Commons Attribution-ShareAlike 2.0 UK: England & Wales License](https://creativecommons.org/licenses/by-sa/2.0/uk/).
+CC-BY 4.0 (c) The JSON Schema Project contributors

Original file line number	Diff line number	Diff line change
`@@ -105,4 +105,4 @@ TSC: The JSON Schema Technical Steering Committee, delegated technical leadershi`
`105`	`105`
`106`	`106`	`---`
`107`	`107`
`108`		`-This work is licensed under a [Creative Commons Attribution-ShareAlike 2.0 UK: England & Wales License](https://creativecommons.org/licenses/by-sa/2.0/uk/).`
	`108`	`+CC-BY 4.0 (c) The JSON Schema Project contributors`