Doc: sync from Wiki, generate HTML

Closes #291
Fixes #227

Modifications
 - HTML content: match the new Wiki structure
 - Makefile
   - generate a custom HTML sidebar
   - include the sidebar on all pages
   - infer and prepend page titles
   - handle relative links
   - add title metadata, e.g. Shaarli - <Page Name>

Signed-off-by: VirtualTam <virtualtam@flibidi.net>

1 files changed, 15 insertions, 0 deletions

diff --git a/doc/RSS-feeds.md b/doc/RSS-feeds.md
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+#RSS feeds
+### RSS Feeds or Picture Wall for a specific search/tag
+It is possible to filter RSS/ATOM feeds and Picture Wall on a Shaarli to **only display results of a specific search, or for a specific tag**.
+
+For example, if you want to subscribe only to links tagged `photography`:
+- Go to the desired Shaarli instance.
+- Search for the `photography` tag in the _Filter by tag_ box. Links tagged `photography` are displayed.
+- Click on the `RSS Feed` button.
+- You are presented with an RSS feed showing only these links. Subscribe to it to receive only updates with this tag.
+- The same method **also works for a full-text search** (_Search_ box) **and for the Picture Wall** (want to only see pictures about `nature`?)
+- You can also build the URLs manually: 
+    - `https://my.shaarli.domain/?do=rss&searchtags=nature`
+    - `https://my.shaarli.domain/links/?do=picwall&searchterm=poney`
+
+![(images/rss-filter-1.png) !]((images/rss-filter-1.png)-!.html)(images/rss-filter-2.png)