Add web build docs, many other minor doc changes

docs/topics/web.md

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+# Web builds
+In addition to your usual Node applications, discord.js has special distributions available that are capable of running in web browsers.
+This is useful for client-side web apps that need to interact with the Discord API.
+[Webpack 2](https://webpack.js.org/) is used to generate these builds
+
+## Usage
+You can obtain your desired version of discord.js' web build from the [webpack branch](https://github.com/hydrabolt/discord.js/tree/webpack) of the GitHub repository.
+There is a file for each branch and version of the library, and the ones ending in `.min.js` are minified to substantially reduce the size of the source code.
+
+Include the file on the page just as you would any other JS library, like so:
+```html
+<script type="text/javascript" src="discord.VERSION.min.js"></script>
+```
+
+Rather than importing discord.js with `require('discord.js')`, the entire `Discord` object is available as a global (on the `window`) object.
+The usage of the API isn't any different from using it in Node.js.
+
+## Restrictions
+- Any voice-related functionality is unavailable, as there is currently no audio encoding/decoding capabilities without external native libraries,
+  which web browsers do not support.
+- The ShardingManager cannot be used, since it relies on being able to spawn child processes for shards.
+- Neither of the optional packages (uws and erlpack) are usable, since they're native libraries.
+
+## Example
+```html
+<script type="text/javascript" src="discord.11.0.0.min.js"></script>
+<script type="text/javascript">
+  const client = new Discord.Client();
+
+  client.on('message', msg => {
+    const guildTag = msg.channel.type === 'text' ? `[${msg.guild.name}]` : '[DM]';
+    const channelTag = msg.channel.type === 'text' ? `[#${msg.channel.name}]` : '';
+    console.log(`${guildTag}${channelTag} ${msg.author.username}#${msg.author.discriminator}: ${msg.content}`);
+  });
+
+  client.login('some crazy token');
+</script>
+```