Also accept 'cite' as a valid HTML tag.

doc/snac.5

@@ -58,7 +58,7 @@ converted to related emojis:
 .Ss Accepted HTML
 All HTML tags in entries are neutered except the following ones:
 .Bd -literal
-a p br blockquote ul li
+a p br blockquote ul li cite
 span i b u pre code em strong
 .Ed
 .Pp

format.c

@@ -185,7 +185,7 @@ xs_str *not_really_markdown(const char *content, xs_list **attach)
 
 
 const char *valid_tags[] = {
-    "a", "p", "br", "br/", "blockquote", "ul", "li",
+    "a", "p", "br", "br/", "blockquote", "ul", "li", "cite",
     "span", "i", "b", "u", "pre", "code", "em", "strong", NULL
 };