Add comprehensive project documentation

Create complete documentation set in doc/ folder:

- index.rst: Main project overview, quickstart, architecture
- philosophy.rst: Design principles, KDL rationale, VCS diversity
- roadmap.rst: Phased development plan (Phase 2.5 current, Phase 3 graphs next)
- history.rst: Development timeline, key decisions, lessons learned
- manifest.rst: Updated to v0.2.0, added Fossil docs, schema upgrade notes

Documentation covers:
- Current state (Phase 2.5)
- Complete roadmap through Phase 4
- Visual dependency graph plans (Phase 3)
- Philosophy and anti-corporate stance
- History from origins to present

All documentation in reStructuredText format for website generation.

1 files changed, 20 insertions, 5 deletions

diff --git a/doc/manifest.rst b/doc/manifest.rst
index 9d1d74a..728e515 100644
--- a/doc/manifest.rst
+++ b/doc/manifest.rst
@@ -6,7 +6,7 @@ Setting up for pinning down inputs
 --------------------------------------------------------------------------------
 
 :author: toastal
-:version: 0.1.1
+:version: 0.2.0
 
 .. role:: ab
 .. role:: ac
@@ -18,16 +18,22 @@ Synopsis
 Nixtamal uses :ac:`KDL` for its manifest describing inputs. At the highest
 level, this includes:
 
-• manifest version
+• manifest version (supports schema upgrades via ``nixtamal upgrade``)
 • default hashing algorithm
 • list of inputs
 
-  	• the input kind & its specific attributes
-  	• a command to check if ‘latest’
+  	• the input kind & its specific attributes (Git, Darcs, Pijul, Fossil, etc.)
+  	• a command to check if 'latest'
   	• hashing information
 
 .. note::
 
+   The manifest uses schema versioning (currently 0.2.0). When upgrading
+   nixtamal, use ``nixtamal upgrade`` to migrate manifests between schema
+   versions. The upgrade command creates backups and supports rollback.
+
+.. note::
+
    While :ac:`KDL` Schema Language exists, it seems there is a upcoming `v2
    <https://github.com/kdl-org/kdl/pull/486>`_. It seems to address some issues
    with the v1 :ab:`spec` which would both help, but also render using the
@@ -77,7 +83,7 @@ At a high level these should be seen as
 “kind”
 	There are specific nodes for each different type of supported
 	fetchers/prefetchers: ``file``, ``archive``, ``git``, ``darcs``, ``pijul``
-	(with more to come in the future).
+	``fossil``, ``nilla``.
 ``hash``
 	An optional node for hash algorithm information for a input. The
 	``algorithm`` property will be used when prefetching, locking, & for
@@ -163,6 +169,15 @@ Pijul
 	reference point for getting stable reference; if unsure, try ``channel
 	main``
 
+Fossil
+--------------------------------------------------------------------------------
+
+``repository``
+	`Templated node`_ repository reference for the input
+“reference”
+	``branch`` *or* ``tag`` *or* ``checkin`` node as the reference point for
+	getting stable reference; checkins are SHA1 hashes of commits
+
 
 Templated node
 ================================================================================