Add a directory for proposed specifications

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

docs/.gitignore

@@ -0,0 +1,3 @@
+*.html
+*.pdf
+!PSACryptoDriverModelSpec.pdf

docs/architecture/.gitignore

@@ -1,2 +0,0 @@
-*.html
-*.pdf

docs/proposed/Makefile

@@ -0,0 +1,21 @@
+PANDOC = pandoc
+
+default: all
+
+all_markdown = \
+	       # This line is intentionally left blank
+
+html: $(all_markdown:.md=.html)
+pdf: $(all_markdown:.md=.pdf)
+all: html pdf
+
+.SUFFIXES:
+.SUFFIXES: .md .html .pdf
+
+.md.html:
+	$(PANDOC) -o $@ $<
+.md.pdf:
+	$(PANDOC) -o $@ $<
+
+clean:
+	rm -f *.html *.pdf

docs/proposed/README

@@ -0,0 +1,4 @@
+The documents in this directory are proposed specifications for Mbed
+TLS features. They are not implemented yet, or only partially
+implemented. Please follow activity on the `development` branch of
+Mbed TLS if you are interested in these features.