tidy-up: miscellaneous

- fix typos and wording in documentation and comments.
- KNOWN_BUGS: merge duplicate H1 section.
- test_10_proxy: delete stray expressions.
- Perl: `while()` -> `while(1)`.
- Perl: fix indent, whitespace, drop redundant quotes and parentheses.
- fix casing: URL, SSL, Windows.
- badwords: readd `threadsafe`, add `well-known` (and fix it).
- replace `WinXP` -> `Windows XP` to match other uses.

Closes #21646

docs/examples/cacertinmem.c

@@ -166,10 +166,10 @@ int main(void)
 
     /* use a fresh connection (optional) this option seriously impacts
      * performance of multiple transfers but it is necessary order to
-     * demonstrate this example. recall that the ssl ctx callback is only
+     * demonstrate this example. recall that the SSL ctx callback is only
      * called _before_ an SSL connection is established, therefore it does not
      * affect existing verified SSL connections already in the connection
-     * cache associated with this handle. normally you would set the ssl ctx
+     * cache associated with this handle. normally you would set the SSL ctx
      * function before making any transfers, and not use this option.
      */
     curl_easy_setopt(curl, CURLOPT_FRESH_CONNECT, 1L);

docs/examples/simplessl.c

@@ -22,7 +22,7 @@
  *
  ***************************************************************************/
 /* <DESC>
- * Shows HTTPS usage with client certs and optional ssl engine use.
+ * Shows HTTPS usage with client certs and optional SSL engine use.
  * </DESC>
  */
 #ifdef _MSC_VER

docs/examples/smooth-gtk-thread.c

@@ -125,7 +125,7 @@ static void *create_thread(void *progress_bar)
   pthread_t tid[NUMT];
   int i;
 
-  /* Make sure I do not create more threads than urls. */
+  /* Make sure I do not create more threads than URLs. */
   for(i = 0; i < NUMT && i < num_urls; i++) {
     int error = pthread_create(&tid[i],
                                NULL, /* default attributes please */

docs/examples/sslbackend.c

@@ -22,7 +22,7 @@
  *
  ***************************************************************************/
 /* <DESC>
- * Shows HTTPS usage with client certs and optional ssl engine use.
+ * Shows HTTPS usage with client certs and optional SSL engine use.
  * </DESC>
  */
 #include <assert.h>