Various doc fixes.

Fix typo in NOTES.WIN: this -> these

Fix wrong capital letter in certificates.txt

Make number of characters in each line more even
Remove redundant empty line

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3986)

NOTES.WIN

@@ -6,7 +6,7 @@
  --------------------------------------------------
 
  In addition to the requirements and instructions listed in INSTALL,
- this are required as well:
+ these are required as well:
 
  - You need Perl.  We recommend ActiveState Perl, available from
    https://www.activestate.com/ActivePerl. Another viable alternative

doc/HOWTO/certificates.txt

@@ -90,7 +90,7 @@ Your key most definitely is if you have followed the examples above.
 However, some (most?) certificate authorities will encode them with
 things like PKCS7 or PKCS12, or something else.  Depending on your
 applications, this may be perfectly OK, it all depends on what they
-know how to decode.  If not, There are a number of OpenSSL tools to
+know how to decode.  If not, there are a number of OpenSSL tools to
 convert between some (most?) formats.
 
 So, depending on your application, you may have to convert your

doc/HOWTO/proxy_certificates.txt

@@ -18,7 +18,7 @@ rights to some other entity (a computer process, typically, or sometimes to the
 user itself).  This allows the entity to perform operations on behalf of the
 owner of the EE certificate.
 
-See http://www.ietf.org/rfc/rfc3820.txt for more information.
+See https://www.ietf.org/rfc/rfc3820.txt for more information.
 
 
 2. A warning about proxy certificates