docs: update documentation for May 12 compiler fixes

- CLJNIM_RECOMMENDATIONS.md: mark all 12 recommendations as implemented
- README.md: add --lib-path, first-class functions, multi-arity, rest params
- User guides (EN/BG): add sections for docstrings, multi-arity, rest params,
  keyword-as-function, first-class functions, loop/recur, --lib-path flag
- TASKS.md: add Phase 11 with all BRing compiler fixes

docs/en/05-user-guide.md

@@ -33,6 +33,21 @@ Generates a `.nim` file from Clojure source.
 ```
 Compiles to Nim, then to C, then to a binary, and runs it.
 
+### Global Flags
+
+#### `--lib-path <dir>` — Custom Library Directory
+Override the default `lib/` search path. Checked before `CLJNIM_LIB_PATH` env var and built-in paths.
+
+```bash
+./cljnim --lib-path ./my_project/lib run app.clj
+```
+
+Environment variable alternative:
+```bash
+export CLJNIM_LIB_PATH=./my_project/lib
+./cljnim run app.clj
+```
+
 ### `read` — Parse and Print AST
 ```bash
 ./cljnim read examples/hello.clj
@@ -61,8 +76,24 @@ Shows the Clojure AST as S-expressions.
 (defn greet [name]
   (println "Hello, " name))
 
+; Function with docstring
+(defn greet "Says hello to someone" [name]
+  (str "Hello, " name))
+
+; Multi-arity function
+(defn greet-multi
+  ([name] (greet-multi name "Hello"))
+  ([name greeting] (str greeting ", " name)))
+
+; Function with rest parameters
+(defn sum-all [x & rest]
+  (+ x (reduce + rest)))
+
 ; Call a function
 (greet "World")
+(greet-multi "Alice")          ;; => "Hello, Alice"
+(greet-multi "Alice" "Hi")     ;; => "Hi, Alice"
+(sum-all 1 2 3 4)              ;; => 10
 
 ; Arithmetic
 (+ 1 2 3)      ; => 6
@@ -88,6 +119,10 @@ Shows the Clojure AST as S-expressions.
 ; Keywords
 (def person {:name "Alice" :age 30})
 
+; Keyword as function (lookup in map)
+(:name person)                 ;; => "Alice"
+(:age person)                  ;; => 30
+
 ; Maps and sets use persistent HAMT data structures
 ; with structural sharing and O(log₃₂ n) operations.
 ```
@@ -102,6 +137,33 @@ Shows the Clojure AST as S-expressions.
 (println (factorial 5))  ; => 120
 ```
 
+### First-Class Functions
+User-defined functions can be passed as values to higher-order functions:
+
+```clojure
+(defn square [x] (* x x))
+(defn odd? [x] (= 1 (mod x 2)))
+
+(map square [1 2 3 4])         ;; => [1 4 9 16]
+(filter odd? [1 2 3 4])        ;; => [1 3]
+(apply + [1 2 3])              ;; => 6
+```
+
+### Loop / Recur
+```clojure
+(defn find-header [headers name]
+  (loop [pairs (seq headers)]
+    (if (empty? pairs)
+      nil
+      (let [[k v] (first pairs)]
+        (if (= k name)
+          v
+          (recur (rest pairs)))))))
+
+(find-header [[:content-type "text/html"] [:accept "*/*"]] :accept)
+;; => "*/*"
+```
+
 ## AI REPL Guide
 
 The JSON REPL is designed for programmatic interaction.