New logo and license text. Closes mesonbuild#4921. [skip ci]

Author: jpakkane

docs/markdown/legal.md

@@ -1,12 +1,23 @@
 # Legal information
 
-Meson is copyrighted by all members of the Meson development team. Meson is licensed under the [Apache 2 license].
+Meson is copyrighted by all members of the Meson development team.
+Meson is licensed under the [Apache 2 license].
 
 Meson is a registered trademark of Jussi Pakkanen.
 
+## Meson logo licensing
+
+Meson's logo is (C) Jussi Pakkanen and used by the Meson project with
+specific permission. It is not licensed under the same terms as the
+rest of the project.
+
+If you are a third party and want to use the Meson logo, you must
+first must obtain written permission from Jussi Pakkanen.
+
 ## Website licensing
 
-The meson website content is released under [Creative Commons Attribution-ShareAlike 4.0 International].
+The meson website content is released under [Creative Commons
+Attribution-ShareAlike 4.0 International].
 
 All code samples on the website are released under [CC0 1.0 Universal].