Fix comments for doxygen (#16)

* Fix comments for doxygen

* Add documentation and update readme.

docs/Improvements_and_updates.md

@@ -0,0 +1,99 @@
+# Improvements and updates
+
+# Server  
+
+NimBLECharacteristic::setValue(const T &s)  
+NimBLEDescriptor::setValue(const T &s)  
+
+Now use a template to accomodate standard and custom types/values.  
+
+**Example**
+```
+struct my_struct{
+    uint8_t  one;
+    uint16_t two;
+    uint32_t four;
+    uint64_t eight;
+    float    flt;
+}myStruct;
+        
+    myStruct.one = 1;
+    myStruct.two = 2;
+    myStruct.four = 4;
+    myStruct.eight = 8;
+    myStruct.flt = 1234.56;
+
+    pCharacteristic->setValue(myStruct);
+ ```
+This will send the struct to the recieving client when read or a notification sent.  
+
+NimBLECharacteristic::getValue now takes an optional timestamp parameter which will update it's value with  
+the time the last value was recieved. In addition an overloaded template has been added to retrieve the value  
+as a type specified by the user.  
+
+**Example**
+```
+    time_t timestamp;
+    myStruct = pCharacteristic->getValue<myStruct>(&timestamp); // timestamp optional
+```
+<br/>
+
+**Advertising will automatically start when a client disconnects.**  
+
+A new method `NimBLEServer::advertiseOnDisconnect(bool)` has been implemented to control this, true(default) = enabled.  
+<br/>
+
+# Client  
+
+NimBLERemoteCharacteristic::readValue(time_t\*, bool)  
+NimBLERemoteDescriptor::readValue(bool)  
+
+Have been added as templates to allow reading the values as any specified type.   
+
+**Example**
+```
+struct my_struct{
+    uint8_t  one;
+    uint16_t two;
+    uint32_t four;
+    uint64_t eight;
+    float    flt;
+}myStruct;
+
+    time_t timestamp;
+    myStruct = pRemoteCharacteristic->readValue<myStruct>(&timestamp); // timestamp optional
+```  
+<br/>
+
+NimBLERemoteCharacteristic::registerForNotify  
+Has been **deprecated** as now the internally stored characteristic value is updated when notification/indication is recieved.  
+
+NimBLERemoteCharacteristic::subscribe and NimBLERemoteCharacteristic::unsubscribe have been implemented to replace it.  
+A callback is no longer requred to get the most recent value unless timing is important. Instead, the application can call NimBLERemoteCharacteristic::getValue to  
+get the last updated value any time.  
+
+In addition NimBLERemoteCharacteristic::readValue and NimBLERemoteCharacteristic::getValue take an optional timestamp parameter which will update it's value with  
+the time the last value was recieved.  
+
+NimBLEClient::getService will now retrieve only the service specified and not the full database, this preserves resources  
+otherwise wasted retrieving and allocating attributes the user application is not interested in.  
+<br/>
+
+# General  
+To reduce resource use all instances of std::map have been replaced with std::vector.  
+
+Use of FreeRTOS::Semaphore has been removed as it was consuming too much ram, the related files have been left in place to accomodate application use.  
+
+Operators `==`, `!=` and `std::string` have been added to NimBLEAddress and NimBLEUUID for easier comparison and logging.  
+
+New constructor for NimBLEUUID(uint32_t, uint16_t, uint16_t, uint64_t) added to lower memory use vs string construction. See: [#21](https://github.com/h2zero/NimBLE-Arduino/pull/21).   
+
+Security/pairing operations are now handled in the respective NimBLEClientCallbacks and NimBLEServerCallbacks classes, NimBLESecurity(deprecated) remains for backward compatibility.  
+
+Configuration options have been added to add or remove debugging information, when disabled (default) significatly reduces binary size.  
+In ESP-IDF the options are in menuconfig: `Main menu -> ESP-NimBLE-cpp configuration`.  
+For Arduino the options must be commented / uncommented in nimconfig.h.   
+
+Many more internal improvements have been made as well, this is a brief overview. Refer to the class docs for futher information on class specifics.  
+<br/>  
+