Replace Riot with Element in docs and comments

This only covers the simple cases of references to issues and repos. More
complex areas, such as deployment scripts, will be handled separately.

Part of https://github.com/vector-im/element-web/issues/14864

test/components/views/rooms/RoomSettings-test.js

@@ -177,7 +177,7 @@ describe.skip('RoomSettings', () => {
                         'm.room.history_visibility': 50,
                         'm.room.power_levels': 50,
                         'm.room.topic': 50,
-                        // TODO: Enable support for m.widget event type (https://github.com/vector-im/riot-web/issues/13111)
+                        // TODO: Enable support for m.widget event type (https://github.com/vector-im/element-web/issues/13111)
                         'im.vector.modular.widgets': 50,
                     },
                 },

test/editor/deserialize-test.js

@@ -204,7 +204,7 @@ describe('editor/deserialize', function() {
             expect(parts[3]).toStrictEqual({type: "newline", text: "\n"});
             expect(parts[4]).toStrictEqual({type: "plain", text: "```"});
         });
-        // failing likely because of https://github.com/vector-im/riot-web/issues/10316
+        // failing likely because of https://github.com/vector-im/element-web/issues/10316
         xit('code block with no trailing text and no newlines', function() {
             const html = "<pre><code>0xDEADBEEF</code></pre>";
             const parts = normalize(parseEvent(htmlMessage(html), createPartCreator()));

test/end-to-end-tests/install.sh

@@ -2,6 +2,6 @@
 # run with PUPPETEER_SKIP_CHROMIUM_DOWNLOAD=true sh install.sh if chrome is already installed
 set -e
 ./synapse/install.sh
-# local testing doesn't need a Riot fetched from master,
+# local testing doesn't need a Element fetched from master,
 # so not installing that by default
 yarn install