Style: Misc docs and comment style and language fixes

- Removed empty paragraphs in XML.
- Consistently use bold style for "Example:", on a new line.
- Fix usage of `[code]` when hyperlinks could be used (`[member]`, `[constant]`).
- Fix invalid usage of backticks for inline code in BBCode.
- Fix some American/British English spelling inconsistencies.
- Other minor fixes spotted along the way, including typo fixes with codespell.
- Don't specify `@GlobalScope` for `enum` and `constant`.

doc/classes/BitMap.xml

@@ -12,7 +12,7 @@
 		<method name="convert_to_image" qualifiers="const">
 			<return type="Image" />
 			<description>
-				Returns an image of the same size as the bitmap and with a [enum Image.Format] of type [code]FORMAT_L8[/code]. [code]true[/code] bits of the bitmap are being converted into white pixels, and [code]false[/code] bits into black.
+				Returns an image of the same size as the bitmap and with a [enum Image.Format] of type [constant Image.FORMAT_L8]. [code]true[/code] bits of the bitmap are being converted into white pixels, and [code]false[/code] bits into black.
 			</description>
 		</method>
 		<method name="create">