list dependencies for fetching sources

static/build.html

@@ -190,6 +190,21 @@
             <h2 id="build-dependencies">
                 <a href="#build-dependencies">Build dependencies</a>
             </h2>
+
+            <p>Dependencies for fetching and verifying the sources:</p>
+
+            <ul>
+                <li>repo</li>
+                <li>python3 (for repo)</li>
+                <li>git (both for repo and manual usage)</li>
+                <li>gpg (both for repo and manual usage)</li>
+            </ul>
+
+            <p>You can either obtain <code>repo</code> as a distribution package or the
+            self-updating standalone version from the Android Open Source Project. The
+            self-updating variant avoids dealing with out-of-date distribution packages and
+            depends on GPG to verify updates.</p>
+
             <ul>
                 <li>x86_64 Linux build environment (macOS is not supported, unlike AOSP which
                 partially supports it)</li>