[enh] initial structure

docs/dev/plugins.rst

@@ -0,0 +1,45 @@
+Plugins
+-------
+
+Plugins can extend/replace functionality of various components inside
+searx.
+
+example\_plugin.py
+~~~~~~~~~~~~~~~~~~
+
+.. code:: python
+
+    name = 'Example plugin'
+    description = 'This plugin extends the suggestions with the word "example"'
+    default_on = False  # disable by default
+
+    js_dependencies = tuple()  # optional, list of static js files
+    css_dependencies = tuple()  # optional, list of static css files
+
+
+    # attach callback to the post search hook
+    #  request: flask request object
+    #  ctx: the whole local context of the post search hook
+    def post_search(request, ctx):
+        ctx['search'].suggestions.add('example')
+        return True
+
+Currently implemented plugin entry points (a.k.a hooks)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+-  Pre search hook (``pre_search``)
+-  Post search hook (``post_search``)
+-  Result hook (``on_result``) (is called if a new result is added (see
+   https\_rewrite plugin))
+
+Feel free to add more hooks to the code if it is required by a plugin.
+
+TODO
+~~~~
+
+-  Better documentation
+-  More hooks
+-  search hook (is called while searx is requesting results (for
+   example: things like math-solver), the different hooks are running
+   parallel)
+