Add docs generation workflow (ARMmbed#45)

* Add docs generation workflow

* remove extraneous backslash

.github/workflows/docs.yaml

@@ -0,0 +1,37 @@
+name: Documentation
+
+# Controls when the action will run. Triggers the workflow on push or pull request
+# events but only for the master branch
+on:
+  push:
+    branches: [ master ]
+
+jobs:
+  build-documentation:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        submodules: recursive
+
+    - name: Create BUILD folder
+      run: |
+        mkdir -p ${{ github.workspace }}/BUILD
+
+    # Build the HTML documentation
+    - name: Doxygen Action
+      uses: mattnotmitt/doxygen-action@v1.1.0
+      with:
+          doxyfile-path: ./doxyfile_options
+
+    # Deploy the HTML documentation to GitHub Pages
+    - name: GH Pages Deployment
+      uses: peaceiris/actions-gh-pages@v3
+      with:
+        github_token: ${{ secrets.GITHUB_TOKEN }}
+        publish_dir: ./BUILD/html/
+        enable_jekyll: false
+        allow_empty_commit: false
+        force_orphan: true
+        publish_branch: docs-master

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "doxygen-awesome-css"]
+	path = tools/doxygen-awesome-css
+	url = https://github.com/jothepro/doxygen-awesome-css.git

doxyfile_options

@@ -51,7 +51,7 @@ PROJECT_BRIEF          =
 # pixels and the maximum width should not exceed 200 pixels. Doxygen will copy
 # the logo to the output directory.
 
-PROJECT_LOGO           = 
+PROJECT_LOGO           = tools/mbed-ce_55x55.png
 
 # The OUTPUT_DIRECTORY tag is used to specify the (relative or absolute) path
 # into which the generated documentation will be written. If a relative path is
@@ -142,6 +142,17 @@ INLINE_INHERITED_MEMB  = YES
 
 FULL_PATH_NAMES        = NO
 
+# When both GENERATE_TREEVIEW and DISABLE_INDEX are set to YES, then the FULL_SIDEBAR
+# option determines if the side bar is limited to only the treeview area (value NO) or
+# if it should extend to the full height of the window (value YES). Setting this to YES
+# gives a layout similar to https://docs.readthedocs.io with more room for contents, but
+# less room for the project logo, title, and description.
+# If either GENERATE_TREEVIEW or DISABLE_INDEX is set to NO, this option has no effect.
+# The default value is: NO.
+# This tag requires that the tag GENERATE_HTML is set to YES.
+
+FULL_SIDEBAR           = NO
+
 # The STRIP_FROM_PATH tag can be used to strip a user-defined part of the path.
 # Stripping is only done if one of the specified strings matches the left-hand
 # part of the path. The tag can be used to show relative paths in the file list.
@@ -1162,7 +1173,8 @@ HTML_STYLESHEET        =
 # list). For an example see the documentation.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
-HTML_EXTRA_STYLESHEET  = 
+HTML_EXTRA_STYLESHEET  = tools/doxygen-awesome-css/doxygen-awesome.css \
+                         tools/doxygen-awesome-css/doxygen-awesome-sidebar-only.css
 
 # The HTML_EXTRA_FILES tag can be used to specify one or more extra images or
 # other source files which should be copied to the HTML output directory. Note
@@ -1448,7 +1460,7 @@ DISABLE_INDEX          = NO
 # The default value is: NO.
 # This tag requires that the tag GENERATE_HTML is set to YES.
 
-GENERATE_TREEVIEW      = NO
+GENERATE_TREEVIEW      = YES
 
 # The ENUM_VALUES_PER_LINE tag can be used to set the number of enum values that
 # doxygen will group on one line in the generated HTML documentation.
@@ -2101,6 +2113,7 @@ PREDEFINED             = DOXYGEN_ONLY            \
                          DEVICE_QSPI             \
                          DEVICE_STORAGE          \
                          DEVICE_WATCHDOG         \
+                         DEVICE_LOCALFILESYSTEM  \
                          "TFM_LVL=1" \
                          "MBED_DEPRECATED_SINCE(d, m)=" \
                          "MBED_ENABLE_IF_CALLBACK_COMPATIBLE(F, M)=" \