Add new translation language: Galician (#613)

* Added Galician translation (incl. some translated images, mindmap, and pattern template)
* Added @psanxiao as translation lead for Galician

---------

Co-authored-by: Sebastian Spier <[email protected]>

Author: psanxiao

.github/CODEOWNERS

@@ -16,3 +16,5 @@
 /book/zh/           @WillemJiang
 /translation/pt/    @jrcosta @zilio
 /book/pt/           @jrcosta @zilio
+/translation/gl/    @psanxiao
+/book/gl/           @psanxiao

.github/workflows/book.yml

@@ -15,7 +15,7 @@ jobs:
 
     strategy:
       matrix:
-        language: [en, ja, zh, pt-br]
+        language: [en, ja, zh, pt-br, gl]
 
     steps:
     - uses: actions/checkout@v3

TRUSTED-COMMITTERS.md

@@ -25,6 +25,7 @@ While they don't take all responsibilities of a Trusted Committer (yet), they do
 * Japanese - [@yuhattor](https://github.com/yuhattor)
 * Chinese - [@WillemJiang](https://github.com/WillemJiang)
 * Brazilian Portuguese - [@jrcosta](https://github.com/jrcosta), [@zilio](https://github.com/zilio)
+* Galician - [@psanxiao](https://github.com/psanxiao)
 
 ## Hall of Fame (aka Alumni)