fix a few style errors

how-to/eventListeners.rst

@@ -1,6 +1,6 @@
-==========================
+================================
 Working with WebExtension Events
-==========================
+================================
 
 WebExtensions can react on events by attaching a listener. Consider the :ref:`menus.onClicked` event of the menus API:
 

index.rst

@@ -65,7 +65,7 @@ Thunderbird provides the following messenger related WebExtension APIs, which ar
 +-------------------------------+------------------------------------------------------------+
 | :doc:`messageDisplayScripts`  | |messageDisplayScripts-Description|                        |
 |                               |                                                            |
-|                               | *Added in Thunderbird 78.4                                 |
+|                               | *Added in Thunderbird 78.4*                                |
 +-------------------------------+------------------------------------------------------------+
 | :doc:`messages`               | |messages-Description|                                     |
 +-------------------------------+------------------------------------------------------------+
@@ -178,7 +178,6 @@ as well. The APIs listed in the following table are known to work with Thunderbi
 .. _dns: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/dns
 .. _downloads: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/downloads
 .. _extension: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/extension
-.. _experiments: https://firefox-source-docs.mozilla.org/toolkit/components/extensions/webextensions/basics.html#webextensions-experiments
 .. _i18n: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/i18n
 .. _identity: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/identity
 .. _idle: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/idle
@@ -204,7 +203,6 @@ as well. The APIs listed in the following table are known to work with Thunderbi
 .. |dns-Description| replace:: Enables an extension to resolve domain names.
 .. |downloads-Description| replace:: Enables extensions to save files to disk.
 .. |extension-Description| replace:: Utilities related to an extension. Gets URLs to resources packages with an extension. Gets the Window object for some of the extension's pages. Get the values for various settings.
-.. |experiments-Description| replace::
 .. |i18n-Description| replace:: Functions to internationalize an extension. It can be used to get localized strings from locale files packaged with an extension and to find out Thunderbird's current language.
 .. |identity-Description| replace:: Use the identity API to get an OAuth2 authorization code or access token, which an extension can then use to access user data from a service that supports OAuth2 access (such as Google or Facebook).
 .. |idle-Description| replace:: Find out when the user's system is idle, locked, or active.