another set of minor changes

index.html

@@ -127,6 +127,9 @@
 						</div>
 					</div>
 				</section>
+				<section data-background-image="https://nixos.org/manual/nix/stable/figures/user-environments.png"
+					data-background-size="contain">
+				</section>
 				<section>
 					RPath
 					<pre>
@@ -261,9 +264,10 @@
 				<section data-background-iframe="https://nixos.org/manual/nix/unstable/language/index.html"
 					data-background-interactive>
 					<aside class="notes">
-
 					</aside>
 				</section>
+				<section data-background-iframe="https://noogle.dev/" data-background-interactive>
+				</section>
 			</section>
 			<section>
 				<section>
@@ -933,6 +937,9 @@ <h4>Lock file</h4>
 				<section>
 					Development environments: Demo
 				</section>
+				<section data-background-iframe="https://search.nixos.org/packages"
+					data-background-interactive>
+				</section>
 				<section>
 					<pre>
 						<code data-trim class="r-stretch" data-line-numbers="2-6|4|8-28|11-13|15-23|2-6,11-14">
@@ -1050,13 +1057,22 @@ <h4>Lock file</h4>
 						</code>
 					</pre>
 				</section>
-
-
-
 			</section>
 			<section>
 				Declaring your own package: Demo
 			</section>
+			<section>
+				<section>
+					Usefull tools
+				</section>
+				<section>
+						https://github.com/utdemir/nix-tree
+						https://github.com/kamadorueda/alejandra
+						https://github.com/maralorn/nix-output-monitor
+						https://github.com/nix-community/comma
+						https://github.com/Gabriella439/nix-diff
+				</section>
+			</section>
 		</div>
 	</div>