Restoring previous layout of doxygen related files.

These files will undergo further re-organization in the coming
weeks. It is too early to fix on creating a subfolder for doxygen (as
the original pull request suggested).

.gitignore

@@ -1,2 +1,2 @@
 # Ignore the generated Doxygen output
-/apidoc/
+apidoc/

DOXYGEN_FRONTPAGE.md

@@ -16,7 +16,7 @@ examples, please refer to [code under mbed.org](https://developer.mbed.org/teams
 
 ## Supported Services
 
-Currently supported  services include:
+Currently supported reference services include:
 
 * [Battery](@ref BatteryService)
 * [Device Firmware Update (DFU)](@ref DFUService)
@@ -25,4 +25,7 @@ Currently supported  services include:
 * [Heart Rate](@ref HeartRateService)
 * [UART](@ref UARTService)
 * [UriBeacon](@ref URIBeaconConfigService)
-* [iBeacon](@ref iBeacon)
+* [iBeacon](@ref iBeacon)
+
+The [documentation](https://docs.mbed.com/docs/ble-intros/en/latest/AdvSamples/Overview/)
+contains an overview on how to create new, application-specific services.

ble.doxyfile

@@ -664,7 +664,7 @@ WARN_LOGFILE           =
 # directories like "/usr/src/myproject". Separate the files or directories
 # with spaces.
 
-INPUT                  = ../ble ../source ./
+INPUT                  =
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding, which is
@@ -789,7 +789,7 @@ FILTER_SOURCE_PATTERNS =
 # (index.html). This can be useful if you have a project on for instance GitHub
 # and want reuse the introduction page also for the doxygen output.
 
-USE_MDFILE_AS_MAINPAGE =
+USE_MDFILE_AS_MAINPAGE = DOXYGEN_FRONTPAGE.md
 
 #---------------------------------------------------------------------------
 # configuration options related to source browsing

doxygen/Makefile

@@ -1,12 +0,0 @@
-# Makefile used to generate the API documentation using Doxygen
-
-.PHONY: apidoc apidoc_clean
-
-all: apidoc
-
-apidoc:
-	mkdir -p apidoc
-	doxygen ble.doxyfile
-
-apidoc_clean:
-	rm -rf apidoc