Doxygen: added the \thirdparty alias.

Doxyfile

@@ -245,6 +245,7 @@ ALIASES                = \
     "tweakableliteral{1}=@brief Tweakable literal parser @xrefitem tweakableliterals \"Tweakable literal parser\" \"Tweakable literal parsers\" Allows using @ref \1 with @ref Corrade::Utility::Tweakable." \
     "collisionoccurenceoperator{2}=@relatesalso \1 @brief Collision occurence of @ref \1 and @ref \2 @see @ref \2::operator%(const \1&) const" \
     "collisionoperator{2}=@relatesalso \1 @brief Collision of @ref \1 and @ref \2 @see @ref \2::operator/(const \1&) const" \
+    "thirdparty=@xrefitem credits-third-party \"Third-party components\" \"Third-party components\"" \
     "todoc=@xrefitem todoc \"Documentation todo\" \"Documentation-related todo list\"" \
     "fn_gl{1}=<a href=\"https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/gl\1.xhtml\">gl\1()</a>" \
     "fn_gl2{2}=<a href=\"https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/gl\2.xhtml\">gl\1()</a>" \

Doxyfile-mcss

@@ -25,6 +25,7 @@ ALIASES                = \
     "tweakableliteral{1}=@brief Tweakable literal parser @xrefitem tweakableliterals \"Tweakable literal parser\" \"Tweakable literal parsers\" Allows using @ref \1 with @ref Corrade::Utility::Tweakable." \
     "collisionoccurenceoperator{2}=@relatesalso \1 @brief Collision occurence of @ref \1 and @ref \2 @see @ref \2::operator%(const \1&) const" \
     "collisionoperator{2}=@relatesalso \1 @brief Collision of @ref \1 and @ref \2 @see @ref \2::operator/(const \1&) const" \
+    "thirdparty=@xrefitem credits-third-party \"Third-party components\" \"Third-party components\"" \
     "todoc=@xrefitem todoc \"Documentation todo\" \"Documentation-related todo list\"" \
     "fn_gl{1}=@m_class{m-dox-external} <a href=\"https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/gl\1.xhtml\">gl\1()</a>" \
     "fn_gl2{2}=@m_class{m-dox-external} <a href=\"https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/gl\2.xhtml\">gl\1()</a>" \

Doxyfile-public

@@ -21,6 +21,7 @@ ALIASES                = \
     "tweakableliteral{1}=@brief Tweakable literal parser @xrefitem tweakableliterals \"Tweakable literal parser\" \"Tweakable literal parsers\" Allows using @ref \1 with @ref Corrade::Utility::Tweakable." \
     "collisionoccurenceoperator{2}=@relatesalso \1 @brief Collision occurence of @ref \1 and @ref \2 @see @ref \2::operator%(const \1&) const" \
     "collisionoperator{2}=@relatesalso \1 @brief Collision of @ref \1 and @ref \2 @see @ref \2::operator/(const \1&) const" \
+    "thirdparty=@xrefitem credits-third-party \"Third-party components\" \"Third-party components\"" \
     "todoc=@todo" \
     "fn_gl{1}=@m_class{m-dox-external} <a href=\"https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/gl\1.xhtml\">gl\1()</a>" \
     "fn_gl2{2}=@m_class{m-dox-external} <a href=\"https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/gl\2.xhtml\">gl\1()</a>" \

doc/coding-style.dox

@@ -91,9 +91,9 @@ appropriately mark the class/function
 
 Additionally to @c \@todoc, @c \@debugoperator, @c \@debugoperatorenum,
 @c \@debugoperatorclassenum, @c \@configurationvalue, @c \@configurationvalueref,
-@c \@tweakableliteral, @c \@cb, @c \@ce, @c \@cpp, @c \@cmake defined
-@ref corrade-coding-style-documentation-commands "the same as in Corrade" and
-all @c \@m_* commands from the [m.css theme](http://mcss.mosra.cz/doxygen/#theme-specific-commands),
+@c \@tweakableliteral, @c \@thirdparty, @c \@cb, @c \@ce, @c \@cpp, @c \@cmake
+defined @ref corrade-coding-style-documentation-commands "the same as in Corrade"
+and all @c \@m_* commands from the [m.css theme](https://mcss.mosra.cz/doxygen/#theme-specific-commands),
 these are defined:
 
 @subsubsection coding-style-documentation-commands-code Code