update manifest and gitignore to expose all installments, update link to part 2 in readme

.gitignore

@@ -1,8 +1,2 @@
-part_2_subscribe_form
-part_3_database_follows
-part_4_posts_streams
-part_5_latest_posts
-part_6_unread_delete
-part_7_extension_ideas
 notes
 target

Cargo.toml

@@ -2,7 +2,7 @@
 
 members = [
     "part_1_sbot_rocket",
-    #"part_2_subscribe_form",
+    "part_2_subscribe_form",
     #"part_3_database_follows",
     #"part_4_posts_streams"
 ]

README.md

@@ -9,7 +9,7 @@ Author: [@glyph](https://mycelial.technology/)
 ## Installments
 
  - [Part 1: Sbot and Web Server](https://git.coopcloud.tech/glyph/lykin_tutorial/src/branch/main/part_1_sbot_rocket)
- - Part 2: Subscription Form and Key Validation
+ - [Part 2: Subscription Form and Key Validation](https://git.coopcloud.tech/glyph/lykin_tutorial/src/branch/main/part_2_subscribe_form)
  - Part 3: Database and Follows
  - Part 4: Posts and Message Streams
  - ...