drivers: adc: ad9081: Add README documentation for AD9081

Added the readme file for the AD9081 driver.

Modified the sphinx drivers_doc.rst file to add the corresponding
source.

Signed-off-by: mc-so <michelleclaire.so@analog.com>

Author: mc-so

doc/sphinx/source/drivers/ad9081.rst

@@ -0,0 +1 @@
+.. include:: ../../../../drivers/adc/ad9081/README.rst

doc/sphinx/source/drivers_doc.rst

@@ -10,22 +10,32 @@ ACCELEROMETERS
    :maxdepth: 1
 
    drivers/adxl355
+
    drivers/adxl38x
 
 ANALOG TO DIGITAL CONVERTERS
 ============================
 .. toctree::
    :maxdepth: 1
 
-   drivers/adm1177
    drivers/ad405x
-   drivers/ad796x
-   drivers/pulsar_adc
+
    drivers/ad7768
+
    drivers/ad7768-1
+
+   drivers/ad796x
+
    drivers/ad9083
+
    drivers/ad9208
 
+   drivers/adm1177
+
+   drivers/pulsar_adc
+   
+   drivers/ad9081
+
 ADC / DAC
 ==========
 .. toctree::
@@ -46,10 +56,15 @@ DIGITAL INPUT/OUTPUT
    :maxdepth: 1
 
    drivers/max14914
+
    drivers/max14919
+
    drivers/max149x6
+
    drivers/max22190
+
    drivers/max22196
+
    drivers/max22200
 
 DIGITAL TO ANALOG CONVERTERS
@@ -58,18 +73,24 @@ DIGITAL TO ANALOG CONVERTERS
    :maxdepth: 1
 
    drivers/ad8460
+
    drivers/max22017
 
 FREQUENCY GENERATORS
 ====================
 .. toctree::
    :maxdepth: 1
 
-   drivers/adf4382
+   drivers/adf4030
+
    drivers/adf4368
+
    drivers/adf4377
+
+   drivers/adf4382
+
    drivers/adf5611
-   drivers/adf4030
+
    drivers/admfm2000
 
 INERTIAL MEASUREMENT UNITS
@@ -92,46 +113,70 @@ METER
    :maxdepth: 1
 
    drivers/ade7816
+
    drivers/ade7913
 
+   drivers/ade9113
+
 RF TRANSCEIVER
 ==============
 .. toctree::
    :maxdepth: 1
 
    drivers/madura
+
    drivers/talise
 
 TEMPERATURE
 ==============
 .. toctree::
    :maxdepth: 1
 
-   drivers/max31827
    drivers/ltc2983
 
+   drivers/max31827
+
+   drivers/max31855
+
 POWER MANAGEMENT
 ================
 .. toctree::
    :maxdepth: 1
 
    drivers/ades1754
+
    drivers/adp1050
+
    drivers/adp1055
+
    drivers/adp5055
+
+   drivers/lt3074
+
+   drivers/lt7170
+
+   drivers/lt7182s
+
+   drivers/lt8491
+
+   drivers/lt8722
+
    drivers/ltc2992
+
    drivers/ltc4162l
+
    drivers/ltc4296
+
    drivers/ltc7841
+
    drivers/ltc7871
+
    drivers/ltm4686
-   drivers/lt3074
-   drivers/lt7170
-   drivers/lt7182s
-   drivers/lt8491
-   drivers/lt8722
+
    drivers/ltp8800
+
    drivers/max17851
+
    drivers/max42500
 
 POTENTIOMETER
@@ -154,4 +199,3 @@ GYROSCOPES
    :maxdepth: 1
 
    drivers/adxrs290
-