ESP8266WiFi library documentation (#2388)

* New section with ESP8266WiFi library documentation

* ESP8266WiFi library documentation

1. Introduction - example, diagnostic, doxygen
2. Station - examples, new doc
3. Soft Access Point - examples, new doc
4. Scan - examples, new doc
5. Client - examples, ref. Arduino, setNoDelay, list of functions
6. Client Secure - examples, loadCertificate, setCertificate, list of
functions
7. Server- examples, ref. Arduino, setNoDelay, list of functions
8. UDP - examples, ref. Arduino, Multicast UDP
9. Generic - examples, onEvent, WiFiEventHandler, persistent, mode, list
of functions

* Fixed numbered list

doc/esp8266wifi/server-class.md

@@ -0,0 +1,54 @@
+---
+title: ESP8266WiFi Server Class
+---
+
+[ESP8266WiFi Library :back:](readme.md#server)
+
+
+## Server Class
+
+Methods documented for the [Server Class](https://www.arduino.cc/en/Reference/WiFiServerConstructor) in [Arduino](https://github.com/arduino/Arduino)
+
+1.  [WiFiServer()](https://www.arduino.cc/en/Reference/WiFiServer)
+2.  [begin()](https://www.arduino.cc/en/Reference/WiFiServerBegin)
+3.  [available()](https://www.arduino.cc/en/Reference/WiFiServerAvailable)
+4.  [write()](https://www.arduino.cc/en/Reference/WiFiServerWrite)
+5.  [print()](https://www.arduino.cc/en/Reference/WiFiServerPrint)
+6.  [println()](https://www.arduino.cc/en/Reference/WiFiServerPrintln)
+
+
+Methods and properties described further down are specific to ESP8266. They are not covered in [Arduino WiFi library](https://www.arduino.cc/en/Reference/WiFi) documentation. Before they are fully documented please refer to information below.
+
+
+### setNoDelay
+
+```cpp
+setNoDelay(nodelay)
+```
+
+With `nodelay` set to `true`, this function will to disable [Nagle algorithm](https://en.wikipedia.org/wiki/Nagle%27s_algorithm). 
+
+This algorithm is intended to reduce TCP/IP traffic of small packets sent over the network by combining a number of small outgoing messages, and sending them all at once. The downside of such approach is effectively delaying individual messages until a big enough packet is assembled.
+
+*Example:*
+```cpp
+server.begin();
+server.setNoDelay(true);
+```
+
+
+### Other Function Calls
+
+```cpp
+bool  hasClient () 
+bool  getNoDelay () 
+virtual size_t  write (const uint8_t *buf, size_t size) 
+uint8_t  status () 
+void  close () 
+void  stop ()
+```
+
+Documentation for the above functions is not yet prepared.
+
+
+For code samples please refer to separate section with [examples :arrow_right:](server-examples.md) dedicated specifically to the Server Class.