Update to the demos README file

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from #22505)

(cherry picked from commit aefb529)

demos/README.txt

@@ -12,30 +12,49 @@ aesgcm.c               Demonstration of symmetric cipher GCM mode encrypt/decryp
 aesccm.c               Demonstration of symmetric cipher CCM mode encrypt/decrypt
 ariacbc.c              Demonstration of symmetric cipher CBC mode encrypt/decrypt
 
-cms:
+cms:                   Demonstrations related to the Cryptographic Message
+                       Syntax (CMS) standard
 
 digest:
 EVP_MD_demo.c          Compute a digest from multiple buffers
 EVP_MD_stdin.c         Compute a digest with data read from stdin
 EVP_MD_xof.c           Compute a digest using the SHAKE256 XOF
 EVP_f_md.c             Compute a digest using BIO and EVP_f_md
 
+encode:
+rsa_encode.c           Encode and decode PEM-encoded RSA keys
+
 encrypt:
 rsa_encrypt.c          Encrypt and decrypt data using an RSA keypair.
 
-encode:
-rsa_encode.c           Encode and decode PEM-encoded RSA keys
+guide:                   Sample code from the OpenSSL Guide tutorials. See
+                         the oss-guide-quic-introduction(7) man page.
+quic-client-block.c:     A simple blocking QUIC client
+quic-client-non-block.c: A simple non-blocking QUIC client
+quic-multi-stream.c:     A simple QUIC client using multiple streams
+tls-client-block.c:      A simple blocking SSL/TLS client
+tls-client-non-block.c:  A simple non-blocking SSL/TLS client
+
+http3:                 Demonstration of how to use OpenSSL's QUIC capabilities
+                       for HTTP/3.
 
 kdf:
 hkdf.c                 Demonstration of HMAC based key derivation
 pbkdf2.c               Demonstration of PBKDF2 password based key derivation
 scrypt.c               Demonstration of SCRYPT password based key derivation
 
+keyexch:
+x25519.c               Demonstration of X25519 based key exchange
+
 mac:
 gmac.c                 Demonstration of GMAC message authentication
 poly1305.c             Demonstration of Poly1305-AES message authentication
 siphash.c              Demonstration of SIPHASH message authentication
 
+pkcs12:
+pkread.c               Print out a description of a PKCS12 file.
+pkwrite.c              Add a password to an existing PKCS12 file.
+
 pkey:
 EVP_PKEY_EC_keygen.c           Generate an EC key.
 EVP_PKEY_RSA_keygen.c          Generate an RSA key.
@@ -44,18 +63,14 @@ EVP_PKEY_DSA_paramgen.c        Generate a DSA param key.
 EVP_PKEY_DSA_paramvalidate.c   Validate a DSA param key.
 EVP_PKEY_DSA_paramfromdata.c   Load a DSA param key using raw data.
 
-smime:
-
-pkcs12:
-pkread.c               Print out a description of a PKCS12 file.
-pkwrite.c              Add a password to an existing PKCS12 file.
-
 signature:
 EVP_EC_Signature_demo.c   Compute and verify an EC signature.
 EVP_DSA_Signature_demo.c  Compute and verify a DSA signature.
 EVP_ED_Signature_demo.c   Compute and verify an ED25519 signature.
 rsa_pss_direct.c          Compute and verify an RSA-PSS signature from a hash
 rsa_pss_hash.c            Compute and verify an RSA-PSS signature over a buffer
 
+smime:                 Demonstrations related to S/MIME
+
 sslecho:
-main.c                 Simple SSL echo client/server.
+main.c                 Simple SSL/TLS echo client/server.