refactor(Missing): remove url prop

Author: std-microblock

src/components/Missing.astro

@@ -1,11 +1,7 @@
 ---
-interface Props {
-  // The expected url of the missing resource
-  url?: string;
-}
 ---
 
-<span class="missing" title={Astro.props.url ?? "Missing Resource"}>
+<span class="missing">
   <slot />
 </span>
 

src/content/docs/cpp/language/basic_concepts.mdx

@@ -12,7 +12,7 @@ import { Revision } from "@components/revision";
 
 This section provides definitions for the specific terminology and the concepts used when describing the C++ programming language.
 
-A C++ program is a sequence of text files (typically header and source files) that contain <Missing url="">declarations</Missing>. They undergo <Missing>translation</Missing> to become an executable program, which is executed when the C++ implementation calls its <DocLink dest="cpp.lang.main">main function</DocLink>.
+A C++ program is a sequence of text files (typically header and source files) that contain <Missing>declarations</Missing>. They undergo <Missing>translation</Missing> to become an executable program, which is executed when the C++ implementation calls its <DocLink dest="cpp.lang.main">main function</DocLink>.
 
 Certain words in a C++ program have special meaning, and these are known as <Missing>keywords</Missing>. Others can be used as <Missing>identifiers</Missing>. <Missing>Comments</Missing> are ignored during translation. C++ programs also contain <Missing>literals</Missing>, the values of characters inside them are determined by <Missing>character sets and encodings</Missing>. Certain characters in the program have to be represented with <Missing>escape sequences</Missing>.