tidy-up: Markdown, clang-format nits

- drop leading indent from Markdown.
- switch to Markdown section markers where missing.
- move `&&` and `||` to the end of the line (C, Perl).
- openssl: add parenthesis to an if sub-expression.
- misc clang-format nits.
- unfold Markdown links.
- SSL-PROBLEMS.md: drop stray half code-fence.

Closes #20402

lib/content_encoding.c

@@ -679,8 +679,8 @@ static const struct Curl_cwtype *find_unencode_writer(const char *name,
     for(cep = transfer_unencoders; *cep; cep++) {
       const struct Curl_cwtype *ce = *cep;
       if((curl_strnequal(name, ce->name, len) && !ce->name[len]) ||
-         (ce->alias && curl_strnequal(name, ce->alias, len)
-                    && !ce->alias[len]))
+         (ce->alias && curl_strnequal(name, ce->alias, len) &&
+          !ce->alias[len]))
         return ce;
     }
   }