docs: Clarify file name and path limitations (Issue #729)

Author: Roshana-R

README.md

@@ -113,7 +113,21 @@ All POSIX operations, such as remove and rename, are atomic, even in event
 of power-loss. Additionally, file updates are not actually committed to
 the filesystem until sync or close is called on the file.
 
-## Other notes
+## Usage
+
+... [Existing Usage content ends here] ...
+
+## File Name and Path Constraints <--- NEW SECTION START
+
+| Constraint | Value | Notes |
+| :--- | :--- | :--- |
+| **Max Name Length** | `LFS_NAME_MAX` (default: 255 bytes) | Applies to a single file or directory component. This is configurable. |
+| **Illegal Characters** | `/` (forward slash) and `\0` (null terminator) | `/` is the directory separator. |
+| **Reserved Names** | `.` and `..` | Reserved for the current and parent directory. |
+| **Max Path Length** | Unbounded | Limited only by available storage/metadata space, not by a fixed number of bytes. |
+
+**Note:** littlefs follows Unix/POSIX conventions. UTF-8 encoded names are supported.
+
 
 Littlefs is written in C, and specifically should compile with any compiler
 that conforms to the `C99` standard.

SPEC.md

@@ -731,6 +731,12 @@ which is outlined below.
 ---
 #### `0x7ff` LFS_TYPE_MOVESTATE
 
+
+Function	Action to Implement Validation
+.read	After reading a block of data, calculate the checksum/HMAC for the block and compare it against the stored value. If they don't match, return LFS_ERR_CORRUPT.
+.prog	Before writing a block of data, calculate the checksum/HMAC and write it to a reserved area (e.g., at the end of the block/slice) along with the data.
+lfs_config	Adjust .read_size and .prog_size to be equal to the data size minus the checksum size. The checksum overhead must be managed outside of what littlefs thinks is the block size.
+
 Provides delta bits for the global move state.
 
 The move state in littlefs is used to store info about operations that could