Revert "Another try for fixing schema.md"

This reverts commit c490d880.

doc/schema.md

@@ -185,7 +185,7 @@ RapidJSON implemented a simple NFA regular expression engine, which is used by d
 |Syntax|Description|
 |------|-----------|
 |`ab`    | Concatenation |
-|<code>a|b</code>   | Alternation |
+|<code>a&#124;b</code>   | Alternation |
 |`a?`    | Zero or one |
 |`a*`    | Zero or more |
 |`a+`    | One or more |
@@ -202,7 +202,7 @@ RapidJSON implemented a simple NFA regular expression engine, which is used by d
 |`[^abc]` | Negated character classes |
 |`[^a-c]` | Negated character class range |
 |`[\b]`   | Backspace (U+0008) |
-|<code>\\|</code>, `\\`, ...  | Escape characters |
+|<code>\\&#124;</code>, `\\`, ...  | Escape characters |
 |`\f` | Form feed (U+000C) |
 |`\n` | Line feed (U+000A) |
 |`\r` | Carriage return (U+000D) |