Update documentation. Add Porting guide. Fix httpd free slot check.

README.md

@@ -182,6 +182,23 @@ This port follows the same model as the POSIX wrapper:
 - Socket wrappers serialize stack access with a mutex
 - Blocking operations wait on callback-driven wakeups (instead of busy polling)
 
+## Documentation
+
+- [API reference](docs/API.md): core stack, socket, and protocol-client APIs
+- [Porting guide](docs/porting_guide.md): designing device drivers (with and without DMA) and porting wolfIP to a new operating system
+
+Module how-tos:
+
+- [TLS over wolfIP](docs/tls_howto.md): running wolfSSL/TLS on wolfIP sockets, the I/O-callback bridge, and non-blocking handshakes
+- [HTTP/HTTPS server](docs/http_server_howto.md): the `src/http/` server module, handler registration, and enabling HTTPS
+- [IPsec ESP](docs/ipsec_esp_howto.md): securing traffic with ESP transport mode, SA setup, and Linux `ip xfrm` interop
+- [wolfGuard (FIPS WireGuard)](docs/wolfguard_howto.md): the in-stack WireGuard tunnel, peer/key setup, and kernel interop
+- [TFTP](docs/tftp_howto.md): the TFTP client/server module, callback wiring, and the firmware-download pattern
+- [DHCP & DNS clients](docs/dhcp_dns_howto.md): acquiring a lease, resolving names, and the poll-loop lifecycle
+- [Advanced IPv4](docs/advanced_ipv4_howto.md): multicast/IGMP, IPv4 forwarding, multiple interfaces, and loopback
+
+- [Migrating from lwIP](docs/migrating_from_lwIP.md): mapping lwIP concepts and APIs onto wolfIP
+
 ## Source Layout
 
 - `src/wolfip.c`: core TCP/IP stack

docs/API.md

@@ -19,6 +19,21 @@ wolfIP is a minimal TCP/IP stack designed for resource-constrained embedded syst
   - TFTP (RFC 1350, RFC 2347, RFC 2348, RFC 2349, RFC 7440) via the reusable `src/tftp/` module
   - UDP (RFC 768) - unicast, optional IPv4 multicast with `IP_MULTICAST`
   - TCP (RFC 793) with options (Timestamps, MSS)
+  - IPsec ESP (RFC 4303) - transport mode, manual keying, with `WOLFIP_ESP`
+
+## Module How-To Guides
+
+The core socket and stack APIs are documented below. Optional modules and
+features have dedicated getting-started guides:
+
+- [TLS over wolfIP](tls_howto.md) — running wolfSSL/TLS on wolfIP sockets (`WOLFSSL_WOLFIP`), the I/O-callback bridge, and non-blocking handshakes.
+- [HTTP/HTTPS server](http_server_howto.md) — the `src/http/` server module (`WOLFIP_ENABLE_HTTP`), handler registration, and enabling HTTPS via a `WOLFSSL_CTX`.
+- [IPsec ESP how-to](ipsec_esp_howto.md) — build with `WOLFIP_ESP`, install Security Associations, and interoperate with Linux `ip xfrm`.
+- [wolfGuard (FIPS WireGuard)](wolfguard_howto.md) — the in-stack WireGuard tunnel (`WOLFGUARD`), peer/key setup, and kernel interop.
+- [TFTP how-to](tftp_howto.md) — the callback-driven, allocation-free TFTP client/server in `src/tftp/`, including the firmware-download pattern.
+- [DHCP & DNS clients](dhcp_dns_howto.md) — acquiring a lease, resolving names with `nslookup`, and the poll-loop lifecycle.
+- [Advanced IPv4](advanced_ipv4_howto.md) — multicast/IGMP, IPv4 forwarding, multiple interfaces, and loopback.
+- [Porting guide](porting_guide.md) — writing device drivers and porting wolfIP to a new OS.
 
 ## Build Integration