Fix mongoose docs generation

PUBLISHED_FROM=331821dcd1f7dc8a94581cd8a9b51aa00a89fddc

docs/c-api/mg_http.h/mg_url_decode.md

@@ -0,0 +1,19 @@
+---
+title: "mg_url_decode()"
+decl_name: "mg_url_decode"
+symbol_kind: "func"
+signature: |
+  int mg_url_decode(const char *src, int src_len, char *dst, int dst_len,
+                    int is_form_url_encoded);
+---
+
+Decodes a URL-encoded string.
+
+Source string is specified by (`src`, `src_len`), and destination is
+(`dst`, `dst_len`). If `is_form_url_encoded` is non-zero, then
+`+` character is decoded as a blank space character. This function
+guarantees to NUL-terminate the destination. If destination is too small,
+then the source string is partially decoded and `-1` is returned.
+*Otherwise,
+a length of the decoded string is returned, not counting final NUL. 
+