Add document for base94_encoder

- Also fix the command line issue

Bug: crashpad:308
Change-Id: I2cace85f472acd049c1916b894c6ec36fe7fcc56
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/2048267
Reviewed-by: Joshua Peraza <jperaza@chromium.org>
Commit-Queue: Tao Bai <michaelbai@chromium.org>

tools/base94_encoder.cc

@@ -68,7 +68,7 @@ int Base94EncoderMain(int argc, char* argv[]) {
 
   bool encoding_valid = false;
   int opt;
-  while ((opt = getopt_long(argc, argv, "d:e", long_options, nullptr)) != -1) {
+  while ((opt = getopt_long(argc, argv, "de", long_options, nullptr)) != -1) {
     switch (opt) {
       case kOptionEncode:
         options.encoding = true;

tools/base94_encoder.md

@@ -0,0 +1,100 @@
+<!--
+Copyright 2020 The Crashpad Authors. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# base94_encoder(1)
+
+## Name
+
+base94_encoder—Encode/Decode the given file
+
+## Synopsis
+
+**base94_encoder** [_OPTION…_] input-file output-file
+
+## Description
+
+Encodes a file for printing safely by compressing and base94 encoding it.
+
+The base94_encoder can decode the input file by base94 decoding and
+uncompressing it.
+
+## Options
+
+ * **-e**, **--encode**
+
+   Compress and encode the input file to a base94 encoded file.
+
+ * **-d**, **--decode**
+
+   Decode and decompress a base94 encoded file.
+
+ * **--help**
+
+   Display help and exit.
+
+ * **--version**
+
+   Output version information and exit.
+
+## Examples
+
+Encode file a to b:
+
+```
+$ base94_encoder --encode a b
+```
+
+Decode file b to a
+
+```
+$ base94_encoder --decode b a
+```
+
+## Exit Status
+
+ * **0**
+
+   Success.
+
+ * **1**
+
+   Failure, with a message printed to the standard error stream.
+
+
+## Resources
+
+Crashpad home page: https://crashpad.chromium.org/.
+
+Report bugs at https://crashpad.chromium.org/bug/new.
+
+## Copyright
+
+Copyright 2020 [The Crashpad
+Authors](https://chromium.googlesource.com/crashpad/crashpad/+/master/AUTHORS).
+
+## License
+
+Licensed under the Apache License, Version 2.0 (the “License”);
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an “AS IS” BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.