More SVN hook docs.

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src/docs/svn_hooks.diviner

@@ -11,9 +11,25 @@ engines.
 To install Arcanist as a pre-commit hook, add this to your svn/hooks/pre-commit:
 
   #!/bin/sh
-  /path/to/arcanist/bin/arc svn-hook-pre-commit $@ 1>&2
+  /usr/local/bin/php -f /path/to/arcanist/bin/arc svn-hook-pre-commit $@ 1>&2
   
 Make sure you make this file executable, or you'll get an error for every commit
-with an unhelpful error message. You also need to specify the full path since
-SVN nukes ENV before executing scripts.
+with an unhelpful error message. You also need to specify the full path to PHP
+since SVN nukes ENV before executing scripts. Alternatively you can specify
+PATH explicitly.
 
+If your project is configured to run linters or lint engines which aren't part
+of Arcanist, specify where to load them from with ##--load-phutil-library##:
+
+  --load-phutil-library=/path/to/library/root
+
+Since SVN commit hooks run without access to a working copy, you'll need to keep
+one checked out somewhere and reference it with ##--load-phutil-library## if you
+build new linters or customize lint engines. For example, your hook might
+look like this:
+
+  #!/bin/sh
+  /usr/local/bin/php -f /path/to/arcanist/bin/arc svn-hook-pre-commit \
+    --load-phutil-library=/path/to/custom/lint/engine \
+    --load-phutil-library=/path/to/custom/unittest/engine \
+    $@ 1>&2