docs: verify and reproduce builds (#6515)

* docs/REPRODUCIBLE: add new

* docs/REPRODUCIBLE: clarify Android requirements

* rename to REPRODUCE

* expand and fix sections

* website

* docs, site: change links to simplex.apk to simplex-aarch64.apk

---------

Co-authored-by: Evgeny Poberezkin <evgeny@poberezkin.com>

website/src/_data/docs_dropdown.json

@@ -32,6 +32,10 @@
             "title": "docs-dropdown-9",
             "url": "/downloads/"
         },
+        {
+            "title": "docs-dropdown-15",
+            "url": "/reproduce/"
+        },
         {
             "title": "docs-dropdown-10",
             "url": "/transparency/"

website/src/_data/docs_sidebar.json

@@ -28,6 +28,7 @@
                 "WEBRTC.md",
                 "XFTP-SERVER.md",
                 "DOWNLOADS.md",
+                "REPRODUCE.md",
                 "TRANSPARENCY.md",
                 "SECURITY.md",
                 "FAQ.md"