docs: touch up dfn spec, include in rtd dev docs (#1948)

Include the DFN specification markdown document in the RTD developer docs section. Includes some minor touchup to the document: expand intro, fix headers for table of contents rendering, turn the attribute list into a formatted table, add some explication.

.build_rtd_docs/conf.py

@@ -60,7 +60,7 @@
 dstdir = "_dev"
 fpth = "DEVELOPER.md"
 src = os.path.join("..", fpth)
-dst = os.path.join(dstdir, fpth)
+dst = os.path.join(dstdir, fpth.lower())
 # clean up an existing _mf6run directory
 if os.path.isdir(dstdir):
     shutil.rmtree(dstdir)
@@ -72,7 +72,7 @@
 # -- copy contributor docs
 fpth = "CONTRIBUTING.md"
 src = os.path.join("..", fpth)
-dst = os.path.join(dstdir, fpth)
+dst = os.path.join(dstdir, fpth.lower())
 shutil.copy(src, dst)
 
 # -- copy style guide
@@ -81,6 +81,12 @@
 dst = os.path.join(dstdir, fpth)
 shutil.copy(src, dst)
 
+# -- copy DFN spec
+fpth = "readme.md"
+src = os.path.join("..", "doc", "mf6io", "mf6ivar", fpth)
+dst = os.path.join(dstdir, "dfn.md")
+shutil.copy(src, dst)
+
 # -- build the deprecations table --------------------------------------------
 print("Build the deprecations markdown table")
 pth = os.path.join("..", "doc", "mf6io", "mf6ivar")

.build_rtd_docs/dev.rst

@@ -7,6 +7,7 @@ This section includes developer instructions and conventions.
    :maxdepth: 1
    :glob:
 
-   _dev/CONTRIBUTING.md
-   _dev/DEVELOPER.md
+   _dev/contributing.md
+   _dev/developer.md
    _dev/styleguide.md
+   _dev/dfn.md

.gitignore

@@ -113,6 +113,7 @@ CMakeFiles/
 .build_rtd_docs/_mf6io
 .build_rtd_docs/_mf6src
 .build_rtd_docs/_mf6run
+.build_rtd_docs/_dev
 latex/
 html/
 xml/