[doc/fix] various fixes to readthedocs

Install breathe in the environment,
Fix typo in doxy.
Remove formats command.

.readthedocs.yml

@@ -10,10 +10,6 @@ sphinx:
   builder: html
   configuration: doc/conf.py
 
-# Optionally build your docs in additional formats such as PDF and ePub
-formats: htmlzip
-
 python:
   install:
-    - method: pip
-      path: breathe
+    - requirements: doc/requirements.txt

doc/aml.doxy

@@ -796,7 +796,7 @@ INPUT                  = ../include \
 			 ../include/aml/dma \
 			 ../include/aml/scratch \
 			 ../include/aml/utils \
-			 ../CONTRIBUTING.markdown
+			 ../CONTRIBUTING.markdown \
 			 img/building-blocks-diagram.png
 
 # This tag can be used to specify the character encoding of the source files

doc/requirements.txt

+breathe